The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. The Company evaluates on an ongoing basis its assumptions, including those related to contingencies, deferred taxes, tax liabilities, useful-life of field equipment, right-of-use assets and lease liabilities, pension liabilities, revenue recognition, and share-based compensation costs. The Company’s management believes that the estimates, judgment and assumptions used are reasonable based upon information available at the time they are made. These estimates, judgments and assumptions can affect the reported amounts of assets and liabilities at the dates of the consolidated financial statements, and the reported amounts of net revenue and expenses during the reporting period. Actual results could differ from those estimates.

The Company finances its operations in U.S. dollars and a substantial portion of its costs and revenues from its primary markets is incurred in U.S. dollars. As such, the Company’s management believes that the U.S. dollar is the currency of the primary economic environment in which NovoCure Limited and certain subsidiaries operate. The Company’s reporting currency is U.S. dollars.

Transactions and balances denominated in U.S. dollars are presented at their original amounts. Monetary accounts maintained in currencies other than the U.S. dollar are re-measured into dollars in accordance with Accounting Standards Codification (ASC) No. 830-10, "Foreign Currency Matters." All transaction gains and losses of the re-measurement of monetary balance sheet items are reflected in the consolidated statements of operations as financial income or expenses, as applicable.

For a subsidiary whose functional currency has been determined to be its local currency, assets and liabilities are translated at year-end exchange rates and statement of operations items are translated at average exchange rates prevailing during the year. Such translation adjustments are recorded as a separate component of accumulated other comprehensive income (loss) in shareholders' equity.

The Company accounts for investments in debt securities in accordance with ASC 320, "Investments—Debt and Equity Securities." Management determines the appropriate classification of its investments in marketable debt securities at the time of purchase and reevaluates such determinations at each balance sheet date. For the years ended December 31, 2019 and 2018, all securities are classified as held-to-maturity since the Company has the intent and ability to hold the securities to maturity and, accordingly, debt securities are stated at amortized cost.

The amortized cost of held-to-maturity securities is adjusted for amortization of premiums and accretion of discounts to maturity and any other than temporary impairment losses. Such amortization and interest are included in the consolidated statement of operations as financial income or expenses, as appropriate.

The Company has restricted cash used as security for the use of Company credit cards, presented in short-term assets. Additionally, the Company has pledged bank deposits to cover bank guarantees related to facility rental agreements, fleet lease agreements and customs payments presented in other long-term assets (see Note 12).

The Company’s trade receivables balance contains billed and unbilled commercial activities. As needed, the Company records an allowance for doubtful accounts by reserving for specifically identified doubtful accounts. The Company periodically reviews its customers’ credit risk and payment history. To date, the Company has not experienced any material credit losses related to counter-party risk.

Inventories are stated at the lower of cost or net realizable value. Cost is determined using the weighted average method. The Company regularly evaluates its ability to realize the value of inventory. If the inventories are deemed damaged, if actual demand for the Company’s delivery systems deteriorates, or if market conditions are less favorable than those projected, inventory write-offs may be required.

Field equipment is stated at cost, net of accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful life of the field equipment, which was determined to be 18 to 36 months. Field equipment is equipment being utilized under service agreements, and accounted for in accordance with ASC 842 on a monthly basis as an operating lease (see Note 2(w)). The Company records a write-off provision for any excess, lost or damaged equipment when warranted based on an assessment of the equipment. Write-offs for equipment are included in cost of revenues. During the years ended December 31, 2019, 2018 and 2017, write-offs for $327, $350, and $195, respectively, were recorded (see Note 7).

The Company’s long-lived assets are reviewed for impairment in accordance with ASC 360-10, "Property, Plant and Equipment," whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. Recoverability of an asset to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted cash flows expected to be generated by the asset. If such asset is considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds its fair value. During the three years ended December 31, 2019, no impairment losses have been identified.

Our Products are comprised of two main components: (1) an electric field generator and (2) transducer arrays and related accessories. We retain title to the electric field generator, and the patient is provided replacement transducer arrays and technical support for the device during the term of treatment. The electric field generator and transducer arrays are always supplied and function together and are not sold on a standalone basis.

In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-9, Revenue from Contracts with Customers (Topic 606) (ASU 2014-9), an updated standard on revenue recognition and issued subsequent amendments to the initial guidance in March 2016, April 2016, May 2016 and December 2016 within ASU 2016-8, 2016-10, 2016-12 and 2016-20, respectively (collectively, "ASC 606"). The core principle of the new standard is for companies to recognize revenue to depict the transfer of goods and services to patients in amounts that reflect the consideration to which the company expects to be entitled in exchange for those goods and services. In addition, the new standard requires expanded disclosures. The Company has adopted the standard effective January 1, 2018 using the modified retrospective method for all contracts. The reported results for 2018 and 2019 reflect the application of ASC 606 guidance while the reported results for 2017 were prepared under the guidance of ASC 605, Revenue Recognition (ASC 605). The amount of revenue recognized in 2018 and 2019 reflects the consideration to which the Company expects to be entitled to receive in exchange for our Products.

1.Identify the contract with a patient. A contract with a patient exists when (i) the Company enters into an enforceable contract with a patient that defines each party’s rights regarding delivery of and payment for a Product, (ii) the contract has commercial substance and (iii) the Company determines that collection of

substantially all consideration for such Product is probable based on the payer’s intent and ability to pay the promised consideration. The evidence of a contract generally consists of a prescription, a patient service agreement and the verification of the assigned payer for the contract and intention to collect.

2.Identify the performance obligations in the contract. Our contracts include the lease of the device, the supply obligation of disposable transducer arrays and technical support for the term of treatment. To the extent a contract includes multiple promised products and/or services, the Company must apply judgment to determine whether those products and/or services are capable of being distinct in the context of the contract. If these criteria are not met the promised products and/or services are accounted for as a combined performance obligation. In the Company’s case, the device, support, and disposables are provided as one inseparable package of monthly treatment for a single monthly fee. For more information, see Note 2(w).

3.Determine the transaction price. The transaction price is determined based on the consideration to which the Company will be entitled in exchange for providing a Product to the patient. To the extent the transaction price includes variable consideration, the Company estimates the amount of variable consideration that should be included in the transaction price utilizing either the expected value method or the most likely amount method depending on the nature of the variable consideration. Variable consideration is included in the transaction price if, in the Company’s judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. The Company has agreements with many payers that define explicit discounts off the gross transaction price. In addition to the explicit discounts negotiated with each payer, the Company expects to receive, in aggregate for a given portfolio, less than the gross revenue net of explicit discounts. ASC 606 requires that the Company recognize this variable consideration as an implicit discount in the billing period. The implicit discount includes both an estimate of claims that will pay at an amount less than billed and an estimate of claims that will not pay within a given time horizon. The implicit discount adjustments to the transaction price are due to concessions, not collectability concerns driven by payer credit risk.

4.Allocate the transaction price to performance obligations in the contract. If a contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. As discussed above, there is a combined performance obligation under the Company’s contracts and, therefore, the monthly transaction price determined for the performance obligation will be recognized over time ratably over the monthly term of the treatment.

5.Recognize revenue when or as the Company satisfies a performance obligation. The Company satisfies performance obligations over time. Revenue is recognized at the time the related performance obligation is satisfied by transferring a promised service to a patient. The patient consumes the benefits of treatment on a daily basis over the monthly term. As this criterion is met, the revenues will be recognized over the monthly term. For more information, see Note 2(w).

At adoption of ASC 606 on January 1, 2018, trade receivables increased by $2,807, deferred revenues increased by $645 and the Company recorded a cumulative impact to its accumulated deficit of $2,162 in 2018. Total deferred revenues balances at December 31, 2019 and 2018 were $19,580 and $18,769, respectively, presented as short-term and long-term liabilities. Unbilled revenues include revenues recognized for therapy provided and not invoiced in the reported period, and are presented as part of accounts receivable.

The Company provides treatment at no charge to patients who meet certain criteria under its charitable care policy. Because the Company does not pursue collection of amounts determined to qualify as charity, they are not reported as revenue. The Company's costs of care provided under charitable care were $2,847, $2,762 and $1,483 for the

The Company does not separately bill its customers for shipping and handling costs associated with shipping Products to its customers. These direct shipping and handling costs of $2,688, $2,936 and $5,322 for the years ended December 31, 2019, 2018 and 2017, respectively are included in Sales and Marketing costs.

The Company accounts for share-based compensation in accordance with ASC 718, "Compensation—Stock Compensation." ASC 718 requires companies to estimate the fair value of share-based compensation awards on the date of grant using an option-pricing model. The value of the award is recognized as an expense over the requisite service periods in the Company’s consolidated statements of operations. The Company's policy is to account for forfeitures as they occur.

The Company applies the Black-Scholes model as it believes it is the most appropriate fair value method for all equity awards and for the Employee Share Purchase Plan (the "ESPP"). For market condition awards, the Company also applies the Monte-Carlo simulation model. The Black-Scholes model requires a number of assumptions, of which the most significant are the share price, expected volatility and the expected award term.

The computation of expected volatility is based on actual historical share price volatility of comparable companies when there is not sufficient historical information for the Company. Expected term of options granted is calculated using the average between the vesting period and the contractual term to the expected term of the options in effect at the time of grant. The Company has historically not paid dividends and has no foreseeable plans to pay dividends and, therefore, uses an expected dividend yield of zero in the option pricing model. The risk-free interest rate is based on the yield of U.S. treasury bonds with equivalent terms.

The carrying amounts of cash and cash equivalents, short-term investments, restricted cash, receivables and prepaid expenses, trade receivables, trade payables and other accounts payable and accrued expenses approximate their fair value due to the short-term maturity of such instruments. Based upon the borrowing terms and conditions currently available to the Company, the carrying values of the long-term loans approximate fair value.

The Company accounts for certain assets and liabilities at fair value under ASC 820, "Fair Value Measurements and Disclosures." Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability.

The hierarchy below lists three levels of fair value based on the extent to which inputs used in measuring fair value are observable in the market. The Company categorizes each of its fair value measurements in one of these three levels based on the lowest level input that is significant to the fair value measurement in its entirety.

or similar assets or liabilities in markets with insufficient volume or infrequent transactions, or other inputs that are observable (model-derived valuations in which significant inputs are observable), or can be derived principally from or corroborated by observable market data; and

The availability of observable inputs can vary from instrument to instrument and is affected by a wide variety of factors, including, for example, the type of instrument, the liquidity of markets and other characteristics particular to the transaction. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment and the instrument is categorized as Level 3.

Basic net income (loss) per share is computed based on the weighted average number of ordinary shares outstanding during each period. Diluted net income per share is computed based on the weighted average number of ordinary shares outstanding during the period, plus potential dilutive shares considered outstanding during the period, in accordance with ASC 260-10, as determined under the treasury stock method. As the inclusion of all potential dilutive shares (deriving from options, RSUs and the ESPP) outstanding would be anti-dilutive, basic and diluted net loss per ordinary share was the same for each full year presented. See Note 19 for additional information regarding the three month periods ended September 30, 2019 and December 31, 2019.

The Company accounts for income taxes in accordance with ASC 740-10, "Income Taxes." ASC 740-10 prescribes the use of the liability method whereby deferred tax asset and liability account balances are determined based on differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company provides a valuation allowance, to reduce deferred tax assets to their estimated realizable value, if needed.

The Company established reserves for uncertain tax positions based on the evaluation of whether or not the Company’s uncertain tax position is "more likely than not" to be sustained upon examination. The Company records interest and penalties pertaining to its uncertain tax positions in the financial statements as income tax expense.

Our cash, cash equivalents, short-term investments and trade receivables are potentially subject to a concentration of risk. Cash, cash equivalents and short-term investments are invested at top tier financial institutions globally. As such, these investments may be in excess of insured limitations or not insured in certain jurisdictions. Generally, these investments may be redeemed upon demand and therefore, bear minimal risk.

The Company has a 401(k) retirement savings plan for its U.S. employees. Each eligible employee may elect to contribute a portion of the employee’s compensation to the plan. Company contributions to the plan are at the sole discretion of the Company's Board of Directors. Currently, the Company provides a matching contribution of 50% of the employee's contributions, up to a maximum of three percent (3%) of the employee's annual salary. The Company began making matching contributions as of January 1, 2019 and, as of December 31, 2019, the Company had made matching contributions in the amount of $978 pursuant to the plan.

The Company sponsors a defined benefit plan (the "Swiss Plan") for all its employees in Switzerland for retirement benefits, as well as benefits on death or long-term disability, whereby the employee and the Company contribute a portion of the employee's compensation to the plan. The Swiss Plan is part of a collective pension fund managed by a top tier insurance company. The Company’s exposure under the Swiss Plan is insured. The Company has financial exposure under the Swiss Plan only in the event that the insurance company does not meet its obligations. The Company accounts for this potential counterparty risk in accordance with ASC 715, "Compensation –

Israeli law generally requires payment of severance pay upon dismissal of an employee or upon termination of employment in certain other circumstances. The Company contributes to employee pension plans to fund its severance liabilities. According to Section 14 of Israel Severance Pay Law, the Company makes deposits on behalf of its employees with respect to the Company’s severance liability and therefore no obligation is provided for in the financial statements. Severance pay liabilities with respect to employees who are not subject to Section 14, are provided for in the financial statements based upon the number of years of service and the latest monthly salary and the related deposits are recorded as an asset based on the cash surrender value. Contributions pursuant to these obligations for the years ended December 31, 2019, 2018 and 2017 amounted to $784, $526 and $506, respectively.

The Company accounts for comprehensive income (loss) in accordance with ASC 220, "Comprehensive Income." ASC 220 establishes standards for the reporting and display of comprehensive income (loss) and its components. Comprehensive income (loss) generally represents all changes in shareholders' equity during the period except those resulting from investments by, or distributions to, shareholders. The accumulated other comprehensive income (loss), net of taxes, relates to a pension liability and foreign currency translation adjustments.

On January 1, 2019, the Company adopted ASU No. 2016-02, Leases (ASC 842). The Company determines if an arrangement is a lease and the classification of that lease at inception based on: (1) whether the contract involves the use of a distinct identified asset, (2) whether the Company obtains the right to substantially all the economic benefits from the use of the asset throughout the period, and (3) whether the Company has a right to direct the use of the asset. The Company elected to not recognize a lease liability or right-of-use ("ROU") asset for leases with a term of twelve months or less. The Company also elected the practical expedient to not separate lease and non-lease components for its leases.

ROU assets represent the right to use an underlying asset for the lease term and lease liabilities represent the obligation to make minimum lease payments arising from the lease. ROU assets are initially measured at amounts, which represents the discounted present value of the lease payments over the lease, plus any initial direct costs incurred. The ROU assets are reviewed for impairment. The lease liability is initially measured at lease commencement date based on the discounted present value of minimum lease payments over the lease term. The implicit rate within the operating leases are generally not determinable; therefore, the Company uses the Incremental Borrowing Rate ("IBR") based on the information available at commencement date in determining the present value of lease payments. The Company’s IBR is estimated to approximate the interest rate on similar terms and payments and in economic environments where the leased asset is located.

Certain leases include options to extend or terminate the lease. An option to extend the lease is considered in connection with determining the ROU asset and lease liability when it is reasonably certain that the Company will exercise that option. An option to terminate is considered unless it is reasonably certain that the Company will not exercise the option.

ASC 842 provides lessors with an optional practical expedient, by class of underlying asset, not to separate non-lease components from the associated lease component and, instead, to account for those components as a single component if the non-lease components otherwise would be accounted for under the new revenue guidance (ASC 606) and both of the following criteria are met:

If the lease component is the predominant component, the Company accounts for all revenues under such lease as a single component in accordance with the new lease accounting standard. Conversely, if the non-lease component is the predominant component, all revenues under such lease are accounted for in accordance with the revenue recognition accounting standard. The Company's operating leases qualify for the single component accounting, and the non-lease component in each of the Company's leases is predominant. Therefore, The Company accounts for all revenues from its operating leases in accordance with the revenue recognition accounting standard.

In 2016, the FASB issued ASU No. 2016-02, "Leases (Topic 842)", which amends the existing standards for lease accounting, requiring lessees to recognize most leases on their balance sheets. The new standard establishes a right-of-use model that requires a lessee to recognize a right-of-use asset and lease liability on the balance sheet for all leases. Leases will be classified as finance or operating. The standard is effective for interim and annual reporting periods beginning after December 15, 2018.

The provisions of ASU 2016-02 are to be applied using a modified retrospective approach. In July 2018, the FASB issued ASU No. 2018-11, "Targeted Improvements - Leases (Topic 842)" (together with ASU 2016-02, "ASC 842"). This update provides an additional (and optional) transition method to adopt the new leases standard. Under this method, an entity initially applies the new leases standard at the adoption date and recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Consequently, the prior comparative period’s financials will remain the same as those previously presented. The Company adopted the new standard as of January 1, 2019 and it has also elected to adopt the package of practical expedients permitted in ASC 842.

Upon implementation of ASC 842, effective January 1, 2019, the Company recorded an increase in right-of-use assets obtained in exchange for lease liabilities of $15,733 on its opening balance sheet. The standard did not have a material impact to the Company's consolidated statements of comprehensive income.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. ASU 2016-13 amends the impairment model to utilize an expected loss methodology in place of the currently used incurred loss methodology, which will result in the more timely recognition of losses. ASU 2016-13 also applies to employee benefit plan accounting, with an effective date of the first quarter of fiscal 2020. The amendments in this update are effective for fiscal years beginning after December 31, 2019, including interim periods within those fiscal years. We have adopted the new standard effective January 1, 2020 and do not expect the adoption of this guidance to have a material impact on the Company's consolidated financial statements.

In August 2018, FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The amendments in this ASU align the requirements for capitalizing implementation costs incurred in a hosting arrangement with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The implementation costs incurred in a hosting arrangement that is a service contract should be presented as a prepaid asset in the balance sheet and expensed over the term of the hosting arrangement to the same line item in the statement of income as the costs related to the hosting fees. The guidance in this ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption is permitted including adoption in any interim period. The amendments should be applied either retrospectively or prospectively to all implementation costs incurred after adoption. The Company is currently evaluating the impact that the standard will have, if any, on its consolidated financial statements and related disclosures.

In August 2018, the FASB issued ASU 2018-14—Compensation—Retirement Benefits—Defined Benefit Plans—General (Topic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans. ASU 2018-14 improves disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. This standard is effective for fiscal years ending after December 15, 2020, for public business entities. Early adoption is permitted. An entity should apply the amendments in this ASU on a retrospective basis to all periods presented. The Company is currently evaluating the impact that the standard will have, if any, on its consolidated financial statements and related disclosures.

In December 2019, the FASB issued Accounting Standard Update No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12). This guidance will be effective for the Company in the first quarter of 2021 on a prospective basis, and early adoption is permitted. The Company is currently evaluating the impact of the new guidance on the Company's consolidated financial statements.