Summary of Significant Accounting Policies	12 Months Ended
Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and include the accounts of the Company and its subsidiaries. Intercompany transactions have been eliminated. Changes in Presentation The presentation of the financial statements for certain prior period amounts has been changed to conform with the current period presentation, including: (i) separate presentation of debt extinguishment expenses from other expense, net, (ii) combined presentation of license and other revenue with digital revenue, (iii) combined presentation of cost of testing services, cost of product, and cost of digital, and (iv) separate presentation of gross profit. These reclassifications had no effect on the reported results of operations. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities and the reported amounts of revenues and expenses in the consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to transaction price estimates used for testing revenue; accrued expenses for clinical studies inventory valuation; the fair value of issued common stock warrants; the fair value of assets and liabilities acquired in a business combination or an assets acquisition (including identifiable intangible assets acquired); the fair value of contingent consideration recorded in connection with a business combination; the grant date fair value assumptions used to estimate stock-based compensation expense; income taxes; impairment of long-lived assets and indefinite-lived assets (including goodwill); and legal contingencies. Actual results could differ from those estimates. Concentrations of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash, cash equivalents and accounts receivable. The Company’s policy is to invest its cash and cash equivalents in money market funds, obligations of U.S. government agencies and government-sponsored entities, commercial paper and various bank deposit accounts. These financial instruments are held in Company accounts at twelve financial institutions. The counterparties to the agreements relating to the Company’s investments consist of financial institutions of high credit standing. The Company is exposed to credit risk in the event of default by the financial institutions to the extent of amounts recorded on the balance sheets that may be in excess of insured limits. The Company is also subject to credit risk from its accounts receivable, which are derived from revenue earned from AlloSure Kidney and AlloMap Heart tests provided for patients located in the U.S. and billed to various third-party payers, from sales of products to distributors, strategic partners and transplant laboratories in Europe, the Middle East, Africa, the U.S., Latin America and other geographic regions, and from sales of digital solutions software. The Company has not experienced any significant credit losses and does not require collateral on receivables. For the years ended December 31, 2019, 2018 and 2017, approximately 55%, 48% and 27%, respectively, of total revenue was billed to Medicare. No other payers represented more than 10% of total revenue for the years ended December 31, 2019, 2018 and 2017. As of December 31, 2019 and 2018, approximately 36% and 27%, respectively, of accounts receivable was due from Medicare. No other payer represented more than 10% of accounts receivable at either December 31, 2019 or 2018. Cash Equivalents Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase. Cash equivalents consist primarily of amounts invested in money market funds. Restricted Cash As a condition of the lease agreements for certain facilities and an agreement with the State of Florida Medicaid, the Company must maintain letters of credit, minimum collateral requirements and a surety bond. These agreements are collateralized by cash. The cash used to support these arrangements of $0.3 million is classified as long-term restricted cash on the accompanying consolidated balance sheets. Inventory Inventory is finished goods, work in progress, and raw materials and consists of reagent plates, testing devices, laboratory supplies, reagents and finished goods kits. Inventories are used in connection with tests performed, and kits produced and may also be used for research and product development efforts. Laboratory supplies subsequently designated for research and product development use are expensed. Obsolete or damaged inventories are written off and excluded from the physical inventory. Inventories at the Company’s Stockholm, Sweden, and Fremantle, Australia locations are stated at the lower of purchased cost, determined on an average cost basis, or net realizable value. Inventories at the Company’s other locations are stated at the lower of actual purchased cost, determined on a first-in, first-out basis, or net realizable value. Property and Equipment, net Property and equipment are stated at cost, less accumulated depreciation. Property and equipment are depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful life is generally three years for machinery, computer and office equipment, and seven years for furniture and fixtures. Leasehold improvements are amortized over the shorter of their estimated useful lives or the remaining lease term. The Company capitalizes certain costs incurred for software developed or obtained for internal use (including hosting arrangements). These costs include software licenses, consulting services, and direct materials, as well as employee payroll and payroll-related costs. Capitalized internal-use software costs are usually amortized over a period of three to five years. Business Combinations The Company determines and allocates the purchase price of an acquired business to the assets acquired and liabilities assumed based on their estimated fair values as of the business combination date, including separately identifiable intangible assets, which are separable from goodwill. The Company bases the estimated fair value of identifiable intangible assets acquired in a business combination on independent valuations that use information and assumptions provided by management, which consider management’s best estimates of inputs and assumptions that a market participant would use. The Company allocates any excess purchase price over the estimated fair value assigned to the net tangible and identifiable intangible assets acquired and liabilities assumed to goodwill. The use of alternative valuation assumptions, including estimated revenue projections, growth rates, royalty rates, cash flows, discount rates, estimated useful lives and probabilities surrounding the achievement of contingent milestones could result in different purchase price allocations and amortization expense in current and future periods. In those circumstances where an acquisition involves a contingent consideration arrangement that meets the definition of a liability under Accounting Standard Codification (“ASC”), Topic 480, Distinguishing Liabilities from Equity, the Company recognizes a liability equal to the fair value of the contingent payments that the Company expects to make as of the acquisition date. The Company remeasures this liability each reporting period and records changes in the fair value as a component of operating expenses. In circumstances where the contingent consideration is classified as equity, the Company recognizes it at fair value at the acquisition date. Contingent consideration classified as equity is not subsequently remeasured. Transaction costs associated with acquisitions are expensed as incurred in general and administrative expenses. Results of operations and cash flows of acquired companies are included in the Company’s operating results from the date of acquisition. Acquired Intangible Assets Amortizable intangible assets include customer relationships, developed technology, trademarks, contracts and acquired in-process technology assets acquired as part of a business combination. Intangible assets subject to amortization are amortized over their estimated useful lives. Acquired in-process technology assets are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. If and when development is complete, which generally occurs if and when regulatory approval to market a product is obtained, the associated assets would be deemed finite-lived and would then be amortized based on their respective estimated useful lives at that point in time. Impairment of Goodwill, Intangible Assets and Long-lived Assets Goodwill Goodwill recorded in a business combination is not subject to amortization. Instead, it is tested for impairment on an annual basis and whenever events or changes in circumstances indicate its carrying amount may not be recoverable. The Company’s annual impairment test date is December 1st. A qualitative assessment is initially made to determine whether it is necessary to perform a quantitative assessment. A qualitative assessment includes, among others, consideration of: (i) past, current and projected future earnings; (ii) recent trends and market conditions; and (iii) valuation metrics involving similar companies that are publicly-traded and acquisitions of similar companies, if available. If this qualitative assessment indicates that it is more likely than not that an impairment exists, or if the Company decides to bypass this option, it proceeds to the quantitative assessment. The quantitative assessment consists of a comparison between the estimated fair value of the Company’s reporting unit and its respective carrying amount including goodwill. Where the carrying value of the reporting unit exceeds its estimated fair value, the Company will record an impairment charge based on that difference. The impairment charge will be limited to the amount of goodwill allocated to that reporting unit. When necessary, to determine the reporting unit’s fair value under the quantitative approach, the Company uses a combination of income and market approaches, such as estimated discounted future cash flows of that reporting unit, multiples of earnings or revenues, and analysis of recent sales or offerings of comparable entities. The Company also considers its market capitalization on the date of the analysis to ensure the reasonableness of the reporting unit’s fair value. In connection with the Company’s annual goodwill assessment on December 1, 2019, the Company performed a qualitative assessment taking into consideration past, current and projected future earnings, recent trends and market conditions; and its market capitalization. Based on this analysis, the Company concluded that it was more likely than not that the fair value of the reporting unit exceeded its carrying amount. As such, it was not necessary to perform the quantitative goodwill impairment assessment at that time. As of December 31, 2019, no impairment of goodwill has been identified. Intangible assets not subject to amortization The Company evaluates the carrying value of intangible assets not subject to amortization, related to acquired in-process technology assets, which are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. Accordingly, amortization of the acquired in-process technology assets will not occur until the products reach commercialization. During the period the assets are considered indefinite-lived, they are tested for impairment on an annual basis, as well as between annual tests if the Company becomes aware of any events occurring or changes in circumstances that would indicate that the fair value of the acquired in-process technology assets are less than their carrying amounts. An impairment loss would be recorded when the fair value of an acquired in-process technology asset is less than its carrying value. If and when development is complete, which generally occurs when the products are made commercially available, the associated acquired in-process technology asset will be deemed finite-lived and will then be amortized based on its estimated useful life. As of December 31, 2019, no impairment of acquired in-process technology assets has been identified. Intangible assets and long-lived assets subject to amortization The Company evaluates its finite-lived intangible assets and its long-lived assets for indicators of possible impairment when events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company then compares the carrying amounts of the assets with the future net undiscounted cash flows expected to be generated by such asset. If an impairment exists, the Company measures the impairment based on the excess carrying value of the asset over the asset’s fair value determined using discounted estimates of future cash flows. The Company has not identified any such impairment losses to date. Fair Value of Financial Instruments Fair value is defined as the price that would be received from selling an asset or the price paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value, the Company considers the principal or most advantageous market in which the Company would transact, and it takes into consideration the assumptions that market participants would use when pricing the asset or liability. The Company’s assessment of the significance of a particular input to the fair value measurement of an asset or liability requires management to make judgments and to consider specific characteristics of that asset or liability. The carrying amounts of certain financial instruments of the Company, including cash equivalents, accounts receivable, accounts payable and accrued liabilities, approximate fair value due to their short maturities. The carrying amount of the contingent consideration liability also represents its fair value. Common Stock Warrants Common stock warrants issued with debt, equity or as standalone financing instruments are recorded as either liabilities or equity in accordance with the respective accounting guidance. Warrants recorded as equity are recorded at their relative fair value determined at the issuance date and are not remeasured after that. Warrants recorded as liabilities are recorded at their fair value and remeasured on each reporting date with changes recorded in change in estimated fair value of common stock warrant liability and derivative liability in the consolidated statements of operations. The Company utilizes a binomial-lattice pricing model, or the Monte Carlo Simulation Model, that involves a market condition simulation to estimate the fair value of the warrants. The application of the Monte Carlo Simulation Model requires the use of a number of complex assumptions including the Company's stock price, expected life of the warrants, stock price volatility determined from the Company's historical stock prices and stock prices of peer companies in the diagnostics industry, and risk-free rates based on the implied yield currently available in the U.S. Treasury zero-coupon issues with a remaining term equal to the expected life of the warrants. Increases (decreases) in these assumptions result in a directionally similar impact to the fair value of the common stock warrant liability. Leases Effective January 1, 2019, the Company adopted Accounting Standard Codification (“ASC”) Topic 842, Leases (“ASC 842”). The Company determines if an arrangement is or contains a lease at contract inception. The Company leases office space and equipment primarily through operating leases with a limited number of finance leases. A right-of-use (“ROU”) asset, representing the underlying asset during the lease term, and a lease liability, representing the payment obligation arising from the lease, are recognized on the consolidated balance sheet at lease commencement based on the present value of the payment obligation. For operating leases, expense is recognized on a straight-line basis over the lease term. For finance leases, interest expense on the lease liability is recognized using the effective interest method and amortization of the ROU asset is recognized on a straight-line basis over the shorter of the estimated useful life of the asset or the lease term. Short-term leases with an initial term of 12 months or less are not recorded on the balance sheet. The present value of lease payments is determined by using the interest rate implicit in the lease, if that rate is readily determinable; otherwise, the Company uses its incremental borrowing rate. The incremental borrowing rate is determined by using the rate of interest that the Company would pay to borrow on a collateralized basis an amount equal to the lease payments for a similar term and in a similar economic environment. As of December 31, 2019, the Company’s leases have remaining terms of 0.5 years to 9.17 years, some of which include options to extend the lease term. The Company’s lease terms may include renewal options that are reasonably certain to be exercised and termination options that are reasonably certain not to be exercised. Certain finance leases also include bargain purchase options of the leased equipment. Revenue The Company recognizes revenue from testing services, products, and digital and other revenue in the amount that reflects the consideration that it expects to be entitled in exchange for goods or services as it transfers control to its customers. Revenue is recorded considering a five-step model that includes identifying the contract with a customer, identifying the performance obligations in the contract, determining the transaction price, allocating the transaction price to the performance obligations, and recognizing revenue when, or as, an entity satisfies a performance obligation. Testing Services Revenue AlloSure Kidney and AlloMap Heart patient tests are ordered by healthcare providers. The Company receives a test requisition form with payer information along with a collected patient blood sample. The Company considers the patient to be its customer and the test requisition form to be the contract. Testing services are performed in the Company’s laboratory. Testing services represent one performance obligation in a contract and are performed when results of the test are provided to the healthcare provider, at a point in time. The healthcare providers that order the tests and on whose behalf CareDx provides testing services are generally not responsible for the payment of these services. The first and second revenue recognition criteria are satisfied when the Company receives a test requisition form with payer information from the healthcare provider. Generally, the Company bills third-party payers upon delivery of an AlloSure Kidney or AlloMap Heart test result to the healthcare provider. Amounts received may vary amongst payers based on coverage practices and policies of the payer. The Company has used the portfolio approach, a practical expedient under ASC Topic 606, Revenue from Contracts with Customers, to identify financial classes of payers. Revenue recognized for Medicare and other contracted payers is based on the agreed current reimbursement rate per test, adjusted for historical collection trends where applicable. The Company estimates revenue for non-contracted payers and self-payers using transaction prices determined for each financial class of payers using history of reimbursements. This includes analysis of an average reimbursement per test and a percentage of tests reimbursed. This estimate requires significant judgment. The Company monitors revenue estimates at each reporting period based on actual cash collections in order to assess whether a revision to the estimate is required. Changes in transaction price estimates are updated quarterly based on actual cash collected or changes made to contracted rates. Product Revenue Product revenue is recognized from the sale of products to end-users, distributors and strategic partners when all revenue recognition criteria are satisfied. The Company generally has a contract or a purchase order from a customer with the specified required terms of order, including the number of products ordered. Transaction prices are determinable and products are delivered and risk of loss passed to the customer upon either shipping or delivery, as per the terms of the agreement. Digital and other revenue Digital revenue is mainly derived from perpetual software license agreements entered into with various transplant centers (customers). The main performance obligations in connection with the Company's perpetual software license agreement are the following: (i) implementation services and delivery of the perpetual software license are considered a single performance obligation, (ii) post contract support ("PCS"). The Company allocates the transaction price to each performance obligation based on relative stand-alone selling prices of each distinct performance obligation. Digital revenue in connection with perpetual software license agreements is recognized over time based on the Company’s satisfaction of each distinct performance obligation in each agreement. Perpetual software license agreements typically require advance payments from customers upon the achievement of certain milestones. The Company records deferred revenue in relation to these agreements when cash payments are received, or invoices are issued in advance of the Company’s performance, and generally recognizes revenue over the contractual term, as performance obligations are fulfilled. In addition, the Company derives digital revenue from software subscriptions. The Company generally bills software subscription fees in advance. Revenue from software subscriptions is deferred and recognized ratably over the subscription term. Cost of Revenue Cost of revenue is presented in a single line on the face of the statement of operations. It represents the total combined costs of providing testing services, products and digital solutions to the Company’s customers. The Company’s cost of revenue associated with each of its revenue sources is as follows: Cost of testing services reflects the aggregate costs incurred in delivering the Company’s testing services. The components of cost of testing services are materials and service costs, direct labor costs, stock-based compensation, equipment and infrastructure expenses associated with testing samples, shipping, logistics and specimen processing charges to collect and transport samples, and allocated overhead including rent, information technology, equipment depreciation, utilities and royalties. Royalties for licensed technology, calculated as a percentage of testing services revenues, are recorded as license fees in cost of testing services at the time the testing services revenues are recognized. Cost of product reflects the aggregate costs incurred in delivering the Company’s products to customers. The components of cost of product are materials costs, manufacturing and kit assembly costs, direct labor costs, equipment and infrastructure expenses associated with preparing kitted products for shipment, shipping, and allocated overhead including rent, information technology, equipment depreciation and utilities. Cost of product also includes amortization of acquired developed technology and adjustments to inventory values, including write-downs of impaired, slow moving or obsolete inventory. Cost of digital revenue and other primarily consists of personnel-related costs associated with developing, installing and maintaining software, depreciation of servers and equipment, amortization of acquired intangible assets, support of the functionality of the software's platforms, including stock based compensation expenses, and allocated costs of facilities and information technology. Research and Development Expenses Research and development expenses, including clinical operations, represent costs incurred to develop diagnostic products and services, high quality evidence to support use of the Company’s tests, as well as continued efforts related to improving the Company’s existing products and digital solutions service lines. These expenses include payroll and related expenses, consulting expenses, laboratory supplies, clinical studies and certain allocated expenses as well as amounts incurred under certain collaborative agreements. Research and development costs are expensed as incurred. The Company records accruals for estimated study costs comprised of work performed by contract research organizations under contract terms. Stock-based Compensation The Company uses the Black-Scholes Model, which requires the use of estimates such as stock price volatility and expected option lives, to value employee stock options. The Company estimates the expected option lives using historical data, volatility using its own historical stock prices and stock prices of peer companies in the diagnostics industry, risk-free rates using the implied yield currently available in the U.S. Treasury zero-coupon issues with a remaining term equal to the expected option lives, and dividend yield using the Company’s expectations and historical data. The fair value of each restricted stock unit is calculated based upon the closing price of the Company’s common stock on the date of the grant. The Company uses the straight-line attribution method for recognizing compensation expense. Compensation expense is recognized on awards ultimately expected to vest and reduced for forfeitures that are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Forfeitures are estimated based on the Company’s historical experience. Compensation expense for stock options issued to nonemployees is calculated using the Black-Scholes Model and is recorded over the service performance period using the straight-line attribution method. Options subject to vesting are required to be periodically remeasured over their service performance period, which is generally the same as the vesting period. Income Taxes The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. The Company’s assessment of an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than 50 percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit may change as new information becomes available. Foreign Currency Translation The functional currency of the Company’s foreign subsidiaries is the local currency for each entity, including the Swedish Krona, Australian dollar and the Euro. The revenue and expenses of such subsidiaries have been translated into U.S. dollars at average exchange rates prevailing during the period. Assets and liabilities have been translated at the rates of exchange on the balance sheet date. The resulting cumulative translation adjustments are reported in other comprehensive loss. Foreign currency translation gains and losses on revenue and expenses are recognized in current operations. Comprehensive Loss Comprehensive loss consists of net loss and other losses affecting stockholders’ equity that, under U.S. GAAP, are excluded from net income or loss. For the Company, such items consist of foreign currency losses on the translation of foreign assets and liabilities. Recent Accounting Pronouncements Effective January 1, 2019, the Company adopted ASC 842 using the optional transition method and applied the standard only to leases that existed at that date. Under the optional transition method, the Company does not need to restate the comparative periods in transition and will continue to present financial information and disclosures for periods before January 1, 2019 in accordance with ASC Topic 840. The Company has also chosen to apply the package of practical expedients for existing leases, which provides relief from reassessing: (i) whether a contract is or contains a lease, (ii) lease classification, and (iii) whether initial direct costs can be capitalized. The Company has also made some accounting policy elections to: (i) allow the Company not to separate nonlease components from lease components, and instead to account for those as a single lease component, and (ii) elect not to recognize a ROU asset and a lease liability for leases with a term of 12 months or less. Upon adoption of ASC 842 on January 1, 2019, the Company recorded a ROU asset of approximately $3.0 million and a lease liability of approximately $3.8 million. The lease liability was determined based on the present value of the remaining minimum lease payments. The ROU asset was determined based on the value of the lease liability, adjusted for the deferred rent balances of approximately $0.8 million, which were previously included in accrued and other liabilities as well as deferred rent, net of current portion. See Note 8 for further details. The standard did not have a material impact on the consolidated statement of cash flows or the consolidated statement of operations. In February 2018, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2018-2, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU 2018-2”). The amendments in ASU 2018-2 allow a reclassification from accumulated other comprehensive income to retained earnings for certain tax effects resulting from the Tax Cuts and Jobs Act (the “Tax Act”). ASU 2018-2 became effective for all interim and annual reporting periods beginning after December 15, 2018 and may be applied retrospectively or as of the beginning of the period of adoption. The Company adopted the standard on January 1, 2019. The adoption of the new standard did not have a material impact on the Company’s consolidated financial statements. In September 2018, the FASB issued ASU No. 2018-7, Compensation - Stock Compensation (ASC Topic 718): Improvements to Nonemployee Share Based Payment Accounting (“ASU 2018-7”). ASU 2018-7 is effective for all interim and annual reporting periods beginning on or after December 15, 2018. The Company adopted ASU 2018-7 on January 1, 2019 applying a modified retrospective approach. On transition, the Company only had nonemployee equity-classified awards with an established measurement date. Accordingly, the Company did not record a cumulative-effect adjustment to retained earnings. In August 2018, the FASB issued ASU No. 2018-15, Intangibles – Goodwill and Other – Internal – Use Software (ASC Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”). ASU 2018-15 is effective for fiscal years beginning after December 15, 2019 and interim periods therein. Early adoption of ASU 2018-15 is permitted including adoption in any interim period. The Company adopted the standard during the fourth quarter of 2019. The Company expects the new standard will impact its prospective consolidated financial statements after adoption related to implementation costs in a cloud computing arrangement if and when entered by the Company. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (ASC Topic 820), which modifies, removes and adds certain disclosure requirements on fair value measurements based on the FASB Concepts Statement, Conceptual Framework for Financial Reporting—Chapter 8: Notes to Financial Statements. The ASU is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020, and all annual and interim reporting period thereafter. The amendments on changes in unrealized gains and losses, the range and weighted-average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted upon issuance of ASU 2018-13. An entity is permitted to early adopt any removed or modified disclosures upon issuance of ASU 2018-13 and delay adoption of the additional disclosures until their effective date. The Company is in the process of assessing the impact that the ASU will have in its consolidated financial statements and disclosures. The Company does not believe adoption of the guidance will have a significant impact on its consolidated financial statements. In September 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments (ASC Topic 326), which amends the FASB’s guidance on the impairment of financial instruments. The ASU adds to U.S. GAAP an impairment model known as the current expected credit loss (“CECL”) model, which is based on expected losses rather than incurred losses. Under the new guidance, an entity recognizes as an allowance its estimate of lifetime expected credit losses, which the FASB believes will result in more timely recognition of such losses. The new CECL standard is effective for public companies for annual reporting periods beginning after December 15, 2019, and interim periods therein. ASU 2016-13 has a greater impact on banks. However, nonbank entities that have financial instruments or other assets such as trade receivables, contract assets, lease receivables, financial guarantees, loans and loan commitments, and held-to-maturity debt securities are subject to the CECL model. The Company adopted the standard on January 1, 2020. The adoption of the new standard did not have a material impact on the Company’s consolidated financial statements.

The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and include the accounts of the Company and its subsidiaries. Intercompany transactions have been eliminated.

The presentation of the financial statements for certain prior period amounts has been changed to conform with the current period presentation, including: (i) separate presentation of debt extinguishment expenses from other expense, net, (ii) combined presentation of license and other revenue with digital revenue, (iii) combined presentation of cost of testing services, cost of product, and cost of digital, and (iv) separate presentation of gross profit. These reclassifications had no effect on the reported results of operations.

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities and the reported amounts of revenues and expenses in the consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to transaction price estimates used for testing revenue; accrued expenses for clinical studies inventory valuation; the fair value of issued common stock warrants; the fair value of assets and liabilities acquired in a business combination or an assets acquisition (including identifiable intangible assets acquired); the fair value of contingent consideration recorded in connection with a business combination; the grant date fair value assumptions used to estimate stock-based compensation expense; income taxes; impairment of long-lived assets and indefinite-lived assets (including goodwill); and legal contingencies. Actual results could differ from those estimates.

Financial instruments that potentially subject the Company to credit risk consist of cash, cash equivalents and accounts receivable. The Company’s policy is to invest its cash and cash equivalents in money market funds, obligations of U.S. government agencies and government-sponsored entities, commercial paper and various bank deposit accounts. These financial instruments are held in Company accounts at twelve financial institutions. The counterparties to the agreements relating to the Company’s investments consist of financial institutions of high credit standing. The Company is exposed to credit risk in the

The Company is also subject to credit risk from its accounts receivable, which are derived from revenue earned from AlloSure Kidney and AlloMap Heart tests provided for patients located in the U.S. and billed to various third-party payers, from sales of products to distributors, strategic partners and transplant laboratories in Europe, the Middle East, Africa, the U.S., Latin America and other geographic regions, and from sales of digital solutions software. The Company has not experienced any significant credit losses and does not require collateral on receivables. For the years ended December 31, 2019, 2018 and 2017, approximately 55%, 48% and 27%, respectively, of total revenue was billed to Medicare. No other payers represented more than 10% of total revenue for the years ended December 31, 2019, 2018 and 2017.

As a condition of the lease agreements for certain facilities and an agreement with the State of Florida Medicaid, the Company must maintain letters of credit, minimum collateral requirements and a surety bond. These agreements are collateralized by cash. The cash used to support these arrangements of $0.3 million is classified as long-term restricted cash on the accompanying consolidated balance sheets.

Inventory is finished goods, work in progress, and raw materials and consists of reagent plates, testing devices, laboratory supplies, reagents and finished goods kits. Inventories are used in connection with tests performed, and kits produced and may also be used for research and product development efforts. Laboratory supplies subsequently designated for research and product development use are expensed. Obsolete or damaged inventories are written off and excluded from the physical inventory. Inventories at the Company’s Stockholm, Sweden, and Fremantle, Australia locations are stated at the lower of purchased cost, determined on an average cost basis, or net realizable value. Inventories at the Company’s other locations are stated at the lower of actual purchased cost, determined on a first-in, first-out basis, or net realizable value.

Property and equipment are stated at cost, less accumulated depreciation. Property and equipment are depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful life is generally three years for machinery, computer and office equipment, and seven years for furniture and fixtures. Leasehold improvements are amortized over the shorter of their estimated useful lives or the remaining lease term.

The Company capitalizes certain costs incurred for software developed or obtained for internal use (including hosting arrangements). These costs include software licenses, consulting services, and direct materials, as well as employee payroll and payroll-related costs. Capitalized internal-use software costs are usually amortized over a period of three to five years.

The Company determines and allocates the purchase price of an acquired business to the assets acquired and liabilities assumed based on their estimated fair values as of the business combination date, including separately identifiable intangible assets, which are separable from goodwill. The Company bases the estimated fair value of identifiable intangible assets acquired in a business combination on independent valuations that use information and assumptions provided by management, which consider management’s best estimates of inputs and assumptions that a market participant would use. The Company allocates any excess purchase price over the estimated fair value assigned to the net tangible and identifiable intangible assets acquired and liabilities assumed to goodwill. The use of alternative valuation assumptions, including estimated revenue projections, growth rates, royalty rates, cash flows, discount rates, estimated useful lives and probabilities surrounding the achievement of contingent milestones could result in different purchase price allocations and amortization expense in current and future periods.

In those circumstances where an acquisition involves a contingent consideration arrangement that meets the definition of a liability under Accounting Standard Codification (“ASC”), Topic 480, Distinguishing Liabilities from Equity, the Company recognizes a liability equal to the fair value of the contingent payments that the Company expects to make as of the acquisition date. The Company remeasures this liability each reporting period and records changes in the fair value as a component of operating expenses. In circumstances where the contingent consideration is classified as equity, the Company recognizes it at fair value at the acquisition date. Contingent consideration classified as equity is not subsequently remeasured.

Transaction costs associated with acquisitions are expensed as incurred in general and administrative expenses. Results of operations and cash flows of acquired companies are included in the Company’s operating results from the date of acquisition.

Amortizable intangible assets include customer relationships, developed technology, trademarks, contracts and acquired in-process technology assets acquired as part of a business combination. Intangible assets subject to amortization are amortized over their estimated useful lives. Acquired in-process technology assets are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. If and when development is complete, which generally occurs if and when regulatory approval to market a product is obtained, the associated assets would be deemed finite-lived and would then be amortized based on their respective estimated useful lives at that point in time.

The Company’s annual impairment test date is December 1st. A qualitative assessment is initially made to determine whether it is necessary to perform a quantitative assessment. A qualitative assessment includes, among others, consideration of: (i) past, current and projected future earnings; (ii) recent trends and market conditions; and (iii) valuation metrics involving similar companies that are publicly-traded and acquisitions of similar companies, if available. If this qualitative assessment indicates that it is more likely than not that an impairment exists, or if the Company decides to bypass this option, it proceeds to the quantitative assessment. The quantitative assessment consists of a comparison between the estimated fair value of the Company’s reporting unit and its respective carrying amount including goodwill. Where the carrying value of the reporting unit exceeds its estimated fair value, the Company will record an impairment charge based on that difference. The impairment charge will be limited to the amount of goodwill allocated to that reporting unit.

When necessary, to determine the reporting unit’s fair value under the quantitative approach, the Company uses a combination of income and market approaches, such as estimated discounted future cash flows of that reporting unit, multiples of earnings or revenues, and analysis of recent sales or offerings of comparable entities. The Company also considers its market capitalization on the date of the analysis to ensure the reasonableness of the reporting unit’s fair value.

In connection with the Company’s annual goodwill assessment on December 1, 2019, the Company performed a qualitative assessment taking into consideration past, current and projected future earnings, recent trends and market conditions; and its market capitalization. Based on this analysis, the Company concluded that it was more likely than not that the fair value of the reporting unit exceeded its carrying amount. As such, it was not necessary to perform the quantitative goodwill impairment assessment at that time. As of December 31, 2019, no impairment of goodwill has been identified.

The Company evaluates the carrying value of intangible assets not subject to amortization, related to acquired in-process technology assets, which are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. Accordingly, amortization of the acquired in-process technology assets will not occur until the products reach commercialization.

During the period the assets are considered indefinite-lived, they are tested for impairment on an annual basis, as well as between annual tests if the Company becomes aware of any events occurring or changes in circumstances that would indicate that the fair value of the acquired in-process technology assets are less than their carrying amounts. An impairment loss would be recorded when the fair value of an acquired in-process technology asset is less than its carrying value. If and when development is complete, which generally occurs when the products are made commercially available, the associated acquired in-process technology asset will be deemed finite-lived and will then be amortized based on its estimated useful life.

The Company evaluates its finite-lived intangible assets and its long-lived assets for indicators of possible impairment when events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company then compares the carrying amounts of the assets with the future net undiscounted cash flows expected to be generated by such asset. If an impairment exists, the Company measures the impairment based on the excess carrying value of the asset over the asset’s fair value determined using discounted estimates of future cash flows. The Company has not identified any such impairment losses to date.

Fair value is defined as the price that would be received from selling an asset or the price paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value, the Company considers the principal or most advantageous market in which the Company would transact, and it takes into consideration the assumptions that market participants would use when pricing the asset or liability. The Company’s assessment of the significance of a particular input to the fair value measurement of an asset or liability requires management to make judgments and to consider specific characteristics of that asset or liability.

The carrying amounts of certain financial instruments of the Company, including cash equivalents, accounts receivable, accounts payable and accrued liabilities, approximate fair value due to their short maturities. The carrying amount of the contingent consideration liability also represents its fair value.

Common stock warrants issued with debt, equity or as standalone financing instruments are recorded as either liabilities or equity in accordance with the respective accounting guidance. Warrants recorded as equity are recorded at their relative fair value determined at the issuance date and are not remeasured after that. Warrants recorded as liabilities are recorded at their fair value and remeasured on each reporting date with changes recorded in change in estimated fair value of common stock warrant liability and derivative liability in the consolidated statements of operations.

The Company utilizes a binomial-lattice pricing model, or the Monte Carlo Simulation Model, that involves a market condition simulation to estimate the fair value of the warrants. The application of the Monte Carlo Simulation Model requires the use of a number of complex assumptions including the Company's stock price, expected life of the warrants, stock price volatility determined from the Company's historical stock prices and stock prices of peer companies in the diagnostics industry, and risk-free rates based on the implied yield currently available in the U.S. Treasury zero-coupon issues with a remaining term equal to the expected life of the warrants. Increases (decreases) in these assumptions result in a directionally similar impact to the fair value of the common stock warrant liability.

Effective January 1, 2019, the Company adopted Accounting Standard Codification (“ASC”) Topic 842, Leases (“ASC 842”). The Company determines if an arrangement is or contains a lease at contract inception. The Company leases office space and equipment primarily through operating leases with a limited number of finance leases. A right-of-use (“ROU”) asset, representing the underlying asset during the lease term, and a lease liability, representing the payment obligation arising from the lease, are recognized on the consolidated balance sheet at lease commencement based on the present value of the payment obligation. For operating leases, expense is recognized on a straight-line basis over the lease term. For finance leases, interest expense on the lease liability is recognized using the effective interest method and amortization of the ROU asset is recognized on a straight-line basis over the shorter of the estimated useful life of the asset or the lease term. Short-term leases with an initial term of 12 months or less are not recorded on the balance sheet.

The present value of lease payments is determined by using the interest rate implicit in the lease, if that rate is readily determinable; otherwise, the Company uses its incremental borrowing rate. The incremental borrowing rate is determined by using the rate of interest that the Company would pay to borrow on a collateralized basis an amount equal to the lease payments for a similar term and in a similar economic environment.

As of December 31, 2019, the Company’s leases have remaining terms of 0.5 years to 9.17 years, some of which include options to extend the lease term. The Company’s lease terms may include renewal options that are reasonably certain to be exercised and termination options that are reasonably certain not to be exercised. Certain finance leases also include bargain purchase options of the leased equipment.

The Company recognizes revenue from testing services, products, and digital and other revenue in the amount that reflects the consideration that it expects to be entitled in exchange for goods or services as it transfers control to its customers. Revenue is recorded considering a five-step model that includes identifying the contract with a customer, identifying the performance obligations in the contract, determining the transaction price, allocating the transaction price to the performance obligations, and recognizing revenue when, or as, an entity satisfies a performance obligation.

AlloSure Kidney and AlloMap Heart patient tests are ordered by healthcare providers. The Company receives a test requisition form with payer information along with a collected patient blood sample. The Company considers the patient to be its customer and the test requisition form to be the contract. Testing services are performed in the Company’s laboratory. Testing services represent one performance obligation in a contract and are performed when results of the test are provided to the healthcare provider, at a point in time.

The healthcare providers that order the tests and on whose behalf CareDx provides testing services are generally not responsible for the payment of these services. The first and second revenue recognition criteria are satisfied when the Company receives a test requisition form with payer information from the healthcare provider. Generally, the Company bills third-party payers upon delivery of an AlloSure Kidney or AlloMap Heart test result to the healthcare provider. Amounts received may vary amongst payers based on coverage practices and policies of the payer. The Company has used the portfolio approach, a practical expedient under ASC Topic 606, Revenue from Contracts with Customers, to identify financial classes of payers. Revenue recognized for Medicare and other contracted payers is based on the agreed current reimbursement rate per test, adjusted for historical collection trends where applicable. The Company estimates revenue for non-contracted payers and self-payers using transaction prices determined for each financial class of payers using history of reimbursements. This includes analysis of an average reimbursement per test and a percentage of tests reimbursed. This estimate requires significant judgment.

The Company monitors revenue estimates at each reporting period based on actual cash collections in order to assess whether a revision to the estimate is required. Changes in transaction price estimates are updated quarterly based on actual cash collected or changes made to contracted rates.

Product revenue is recognized from the sale of products to end-users, distributors and strategic partners when all revenue recognition criteria are satisfied. The Company generally has a contract or a purchase order from a customer with the specified required terms of order, including the number of products ordered. Transaction prices are determinable and products are delivered and risk of loss passed to the customer upon either shipping or delivery, as per the terms of the agreement.

Digital revenue is mainly derived from perpetual software license agreements entered into with various transplant centers (customers). The main performance obligations in connection with the Company's perpetual software license agreement are the following: (i) implementation services and delivery of the perpetual software license are considered a single performance obligation, (ii) post contract support ("PCS"). The Company allocates the transaction price to each performance obligation based on relative stand-alone selling prices of each distinct performance obligation. Digital revenue in connection with perpetual software license agreements is recognized over time based on the Company’s satisfaction of each distinct performance obligation in each agreement.

Perpetual software license agreements typically require advance payments from customers upon the achievement of certain milestones. The Company records deferred revenue in relation to these agreements when cash payments are received, or invoices are issued in advance of the Company’s performance, and generally recognizes revenue over the contractual term, as performance obligations are fulfilled.

Cost of revenue is presented in a single line on the face of the statement of operations. It represents the total combined costs of providing testing services, products and digital solutions to the Company’s customers. The Company’s cost of revenue associated with each of its revenue sources is as follows:

Cost of testing services reflects the aggregate costs incurred in delivering the Company’s testing services. The components of cost of testing services are materials and service costs, direct labor costs, stock-based compensation, equipment and infrastructure expenses associated with testing samples, shipping, logistics and specimen processing charges to collect and transport samples, and allocated overhead including rent, information technology, equipment depreciation, utilities and royalties. Royalties for licensed technology, calculated as a percentage of testing services revenues, are recorded as license fees in cost of testing services at the time the testing services revenues are recognized.

Cost of product reflects the aggregate costs incurred in delivering the Company’s products to customers. The components of cost of product are materials costs, manufacturing and kit assembly costs, direct labor costs, equipment and infrastructure expenses associated with preparing kitted products for shipment, shipping, and allocated overhead including rent, information technology, equipment depreciation and utilities. Cost of product also includes amortization of acquired developed technology and adjustments to inventory values, including write-downs of impaired, slow moving or obsolete inventory.

Cost of digital revenue and other primarily consists of personnel-related costs associated with developing, installing and maintaining software, depreciation of servers and equipment, amortization of acquired intangible assets, support of the functionality of the software's platforms, including stock based compensation expenses, and allocated costs of facilities and information technology.

Research and development expenses, including clinical operations, represent costs incurred to develop diagnostic products and services, high quality evidence to support use of the Company’s tests, as well as continued efforts related to improving the Company’s existing products and digital solutions service lines. These expenses include payroll and related expenses, consulting expenses, laboratory supplies, clinical studies and certain allocated expenses as well as amounts incurred under certain collaborative agreements. Research and development costs are expensed as incurred. The Company records accruals for estimated study costs comprised of work performed by contract research organizations under contract terms.

The Company uses the Black-Scholes Model, which requires the use of estimates such as stock price volatility and expected option lives, to value employee stock options. The Company estimates the expected option lives using historical data, volatility using its own historical stock prices and stock prices of peer companies in the diagnostics industry, risk-free rates using the implied yield currently available in the U.S. Treasury zero-coupon issues with a remaining term equal to the expected option lives, and dividend yield using the Company’s expectations and historical data. The fair value of each restricted stock unit is calculated based upon the closing price of the Company’s common stock on the date of the grant.

The Company uses the straight-line attribution method for recognizing compensation expense. Compensation expense is recognized on awards ultimately expected to vest and reduced for forfeitures that are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Forfeitures are estimated based on the Company’s historical experience.

Compensation expense for stock options issued to nonemployees is calculated using the Black-Scholes Model and is recorded over the service performance period using the straight-line attribution method. Options subject to vesting are required to be periodically remeasured over their service performance period, which is generally the same as the vesting period.

The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized.

The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. The Company’s assessment of an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than 50 percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit may change as new information becomes available.

The functional currency of the Company’s foreign subsidiaries is the local currency for each entity, including the Swedish Krona, Australian dollar and the Euro. The revenue and expenses of such subsidiaries have been translated into U.S. dollars at average exchange rates prevailing during the period. Assets and liabilities have been translated at the rates of exchange on the balance sheet date. The resulting cumulative translation adjustments are reported in other comprehensive loss. Foreign currency translation gains and losses on revenue and expenses are recognized in current operations.

Comprehensive loss consists of net loss and other losses affecting stockholders’ equity that, under U.S. GAAP, are excluded from net income or loss. For the Company, such items consist of foreign currency losses on the translation of foreign assets and liabilities.

Effective January 1, 2019, the Company adopted ASC 842 using the optional transition method and applied the standard only to leases that existed at that date. Under the optional transition method, the Company does not need to restate the comparative periods in transition and will continue to present financial information and disclosures for periods before January 1, 2019 in accordance with ASC Topic 840. The Company has also chosen to apply the package of practical expedients for existing leases, which provides relief from reassessing: (i) whether a contract is or contains a lease, (ii) lease classification, and (iii) whether initial direct costs can be capitalized. The Company has also made some accounting policy elections to: (i) allow the Company not to separate nonlease components from lease components, and instead to account for those as a single lease component, and (ii) elect not to recognize a ROU asset and a lease liability for leases with a term of 12 months or less.

Upon adoption of ASC 842 on January 1, 2019, the Company recorded a ROU asset of approximately $3.0 million and a lease liability of approximately $3.8 million. The lease liability was determined based on the present value of the remaining minimum lease payments. The ROU asset was determined based on the value of the lease liability, adjusted for the deferred rent balances of approximately $0.8 million, which were previously included in accrued and other liabilities as well as deferred rent, net of current portion. See Note 8 for further details.

In February 2018, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2018-2, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU 2018-2”). The amendments in ASU 2018-2 allow a reclassification from accumulated other comprehensive income to retained earnings for certain tax effects resulting from the Tax Cuts and Jobs Act (the “Tax Act”). ASU 2018-2 became effective for all interim and annual reporting periods beginning after December 15, 2018 and may be applied retrospectively or as of the beginning of the period of adoption. The Company adopted the standard on January 1, 2019. The adoption of the new standard did not have a material impact on the Company’s consolidated financial statements.

In September 2018, the FASB issued ASU No. 2018-7, Compensation - Stock Compensation (ASC Topic 718): Improvements to Nonemployee Share Based Payment Accounting (“ASU 2018-7”). ASU 2018-7 is effective for all interim and annual reporting periods beginning on or after December 15, 2018. The Company adopted ASU 2018-7 on January 1, 2019 applying a modified retrospective approach. On transition, the Company only had nonemployee equity-classified awards with an established measurement date. Accordingly, the Company did not record a cumulative-effect adjustment to retained earnings.

In August 2018, the FASB issued ASU No. 2018-15, Intangibles – Goodwill and Other – Internal – Use Software (ASC Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”). ASU 2018-15 is effective for fiscal years beginning after December 15, 2019 and interim periods therein. Early adoption of ASU 2018-15 is permitted including adoption in any interim period. The Company adopted the standard during the fourth quarter of 2019. The Company expects the new standard will impact its prospective consolidated financial statements after adoption related to implementation costs in a cloud computing arrangement if and when entered by the Company.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (ASC Topic 820), which modifies, removes and adds certain disclosure requirements on fair value measurements based on the FASB Concepts Statement, Conceptual Framework for Financial Reporting—Chapter 8: Notes to Financial Statements. The ASU is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020, and all annual and interim reporting period

thereafter. The amendments on changes in unrealized gains and losses, the range and weighted-average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted upon issuance of ASU 2018-13. An entity is permitted to early adopt any removed or modified disclosures upon issuance of ASU 2018-13 and delay adoption of the additional disclosures until their effective date. The Company is in the process of assessing the impact that the ASU will have in its consolidated financial statements and disclosures. The Company does not believe adoption of the guidance will have a significant impact on its consolidated financial statements.

In September 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments (ASC Topic 326), which amends the FASB’s guidance on the impairment of financial instruments. The ASU adds to U.S. GAAP an impairment model known as the current expected credit loss (“CECL”) model, which is based on expected losses rather than incurred losses. Under the new guidance, an entity recognizes as an allowance its estimate of lifetime expected credit losses, which the FASB believes will result in more timely recognition of such losses. The new CECL standard is effective for public companies for annual reporting periods beginning after December 15, 2019, and interim periods therein. ASU 2016-13 has a greater impact on banks. However, nonbank entities that have financial instruments or other assets such as trade receivables, contract assets, lease receivables, financial guarantees, loans and loan commitments, and held-to-maturity debt securities are subject to the CECL model. The Company adopted the standard on January 1, 2020. The adoption of the new standard did not have a material impact on the Company’s consolidated financial statements.