Description of Business and Significant Accounting Policies	12 Months Ended
Dec. 31, 2023
Accounting Policies [Abstract]
Description of Business and Significant Accounting Policies	Description of Business and Significant Accounting Policies Company Calix, Inc. (together with its subsidiaries, “Calix” or the “Company”) was incorporated in August 1999 and is a Delaware corporation. The Company is the leading global provider of a platform (cloud, software and systems) and managed services that focus on the subscriber-facing network, the portion of the network that governs available bandwidth and determines the range and quality of services that can be offered to subscribers. This platform and managed services enable broadband service providers (“BSPs”) of all sizes to innovate and transform their businesses. The Company’s BSP customers are empowered to utilize real-time data and insights from the Calix platform to simplify their businesses and deliver experiences that excite their subscribers. These insights enable BSPs to grow their businesses through increased subscriber acquisition, loyalty and revenue, thereby increasing the value of their businesses and contributions to their communities. Basis of Presentation and Accounting Guidance The accompanying consolidated financial statements have been prepared in accordance with the requirements of the U.S. Securities and Exchange Commission (“SEC”) and U.S. generally accepted accounting principles (“GAAP”). All significant intercompany balances and transactions have been eliminated in consolidation. Any reference in these notes to applicable accounting guidance is meant to refer to the authoritative U.S. GAAP as found in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”). Use of Estimates The preparation of financial statements is in conformity with U.S. GAAP, which requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. For the Company, these estimates include, but are not limited to: allowances for doubtful accounts and sales returns, excess and obsolete inventory, allowances for obligations to its contract manufacturers, valuation of stock-based compensation, useful lives assigned to long-lived assets, standard and extended warranty costs, realizability of deferred tax assets and uncertain tax positions and contingencies. Actual results could differ from those estimates, and such differences could be material to the Company’s financial position and results of operations. Revenue Recognition Revenue is recognized when a performance obligation is satisfied, which occurs when control of the promised goods or services is transferred to the customer, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. Revenue from sales of access and premises systems is recognized when control is transferred to the customer, which is generally when the products are shipped. Revenue from software platform licenses, which provides the customer with a right to use the software as it exists, is generally recognized upfront when made available to the customer. Revenue from cloud-based software subscriptions, customer support, maintenance, extended warranty subscriptions and managed services is generally recognized ratably over the contract term. Revenue from professional services and training is recognized as the services are delivered. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. The Company’s hardware products contain both software and non-software components that function together to deliver the products’ essential functionality and therefore constitutes a single performance obligation as the promise to transfer the individual software and non-software components is not separately identifiable and, therefore, not distinct. Cloud-based software subscriptions can include multi-year agreements with a fixed annual fee for a minimum committed usage level. To the extent that minimum committed usage level each year varies, the Company has concluded that each year represents a distinct stand-ready performance obligation and the transaction price allocated to each performance obligation is recognized as revenue ratably over each annual period. The Company’s contracts may include multiple performance obligations. For such arrangements, the Company allocates the contract’s transaction price to each performance obligation using the relative stand-alone selling price of each distinct good or service in the contract. The Company generally determines stand-alone selling prices based on the prices charged to customers or its best estimate of stand-alone selling price. The Company’s estimate of stand-alone selling price is established considering multiple factors including, but not limited to, geographies, market conditions, competitive landscape, internal costs, gross margin objectives, characteristics of targeted customers and pricing practices. The determination of estimated stand-alone selling price is made through consultation with and formal approval by management, taking into consideration the go-to-market strategy. Cost of Revenue Cost of revenue consists primarily of finished goods inventory purchased from the Company’s contract manufacturers, payroll and related expenses associated with managing the relationships with contract manufacturers, depreciation of manufacturing test equipment, warranty and retrofit costs, excess and obsolete inventory costs, allowances for obligations to its contract manufacturers, shipping charges and amortization of certain intangible assets. It also includes contractor and other costs of services incurred directly related to the delivery of services to customers. Warranty and Retrofit The Company offers limited warranties for its hardware products for a period of one, three or five years, depending on the product type. The Company recognizes estimated costs related to warranty activities as a component of cost of revenue upon product shipment or upon identification of a specific product failure. Under certain circumstances, the Company also provides fixes on specifically identified performance failures for products that are outside of the standard warranty period and recognizes estimated costs related to retrofit activities as a component of cost of revenue upon identification of such product failures. The Company recognizes estimated warranty and retrofit costs when it is probable that a liability has been incurred and the amount of loss is reasonably estimable. The estimates are based upon historical and projected product failure and claim rates, historical costs incurred in correcting product failures and information available related to any specifically identified product failures. Judgment is required in estimating costs associated with warranty and retrofit activities, and the Company's estimates are limited to information available to the Company at the time of such estimates. In some cases, such as when a specific product failure is first identified or a new product is introduced, the Company may initially have limited information and limited historical failure and claim rates upon which to base its estimates, and such estimates may require revision in future periods. The recorded amount is adjusted from time to time for specifically identified warranty and retrofit exposure. Actual warranty and retrofit expenses are charged against the Company’s estimated warranty and retrofit liability when incurred. Factors that affect the Company’s warranty and retrofit liability include the number of active installed units and historical and anticipated rates of warranty and retrofit claims and cost per claim. Stock-Based Compensation Stock-based compensation expense associated with stock options and purchase rights under the Amended and Restated Employee Stock Purchase Plan (the “ESPP”) and the Amended and Restated 2017 Nonqualified Employee Stock Purchase Plan (the “NQ ESPP”) is measured at the grant date based on the fair value of the award and is recognized, net of forfeitures, as expense over the remaining requisite service period (generally the vesting period) on a straight-line basis. The fair value of stock option and employee stock purchase right under the ESPP is estimated at the grant date using the Black-Scholes option valuation model. The fair value of the employee stock purchase right under the NQ ESPP is based on closing market price of the Company’s common stock on the date of grant. Stock-based compensation expense associated with performance stock options (“PSOs”) with graded vesting features and which contain both a performance and a service condition is measured based on fair value of stock options estimated at the grant date using the Black-Scholes option valuation model, and is recognized, net of forfeitures, as expense over the requisite service period using the graded vesting attribution method. Compensation expense is only recognized if the Company has determined that it is probable that the performance condition will be met. The Company reassesses the probability of vesting at each reporting period and adjusts compensation expense based on its probability assessment. Loss Contingencies From time to time, the Company is involved in legal proceedings arising from the normal course of business activities. The Company evaluates the likelihood of an unfavorable outcome of legal proceedings to which it is a party and accrues a loss contingency when the loss is probable and reasonably estimable. Assessing legal contingencies involves significant judgment and estimates, and the outcome of litigation is inherently uncertain and subject to numerous factors outside the Company’s control. Significant judgment is required when the Company assesses the likelihood of any adverse judgments or outcomes, including the potential range of possible losses, and whether losses are probable and reasonably estimable. Because of uncertainties related to these matters, the Company bases its estimates of whether a loss contingency is probable or reasonably possible, as well as the reasonable range of possible losses associated with each loss contingency, only on the information available at the time. As additional information becomes available, and at least quarterly, the Company reassesses the potential liability on each significant matter and may revise its estimates. These revisions could have a material impact on the Company’s business, operating results or financial condition. The actual outcome of these legal proceedings may materially differ from the Company’s estimates of potential liability, which could have a material adverse effect on the Company’s business, operating results or financial condition. Credit Risk and Inventory Supplier Concentrations Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities and accounts receivable. Cash equivalents consist of money market funds and marketable securities with a maturity at the date of purchase of ninety days or less, which are invested through financial institutions in the United States. Deposits in and investments held by these financial institutions may, at times, exceed federally insured limits. The Company has not experienced any losses in such accounts. The Company also has approximately $7.7 million of cash held by its foreign subsidiaries in India, China and the United Kingdom. Management believes that the financial institutions that hold the Company’s cash and cash equivalents are financially sound and, accordingly, minimal credit risk exists with respect to these cash and cash equivalents. The Company depends primarily on a small number of outside contract manufacturers (“CMs”) and original design manufacturers (“ODMs”) for the bulk of its finished goods inventory. The Company generally purchases its products through purchase orders with its suppliers. While the Company seeks to maintain a sufficient supply of its products, the Company’s business and results of operations could be adversely affected by a stoppage or delay in receiving such products, the receipt of defective parts, an increase in price of such products or the Company’s inability to obtain lower prices from its CMs, ODMs and other suppliers in response to competitive pressures. Fair Value of Financial Instruments The carrying amounts of cash and cash equivalents, trade receivables, accounts payable and other accrued liabilities approximate their fair value due to their relatively short-term nature. Marketable securities are valued using quoted market prices in active markets to determine fair value. Cash, Cash Equivalents and Marketable Securities Cash equivalents and marketable securities are stated at amounts that approximate fair value based on quoted market prices. The Company has invested its excess cash primarily in money market funds and highly liquid marketable securities such as U.S. treasury securities, corporate debt instruments, commercial paper and U.S. government securities. The Company considers all investments with maturities of three months or less when purchased to be cash equivalents. Marketable securities represent highly liquid U.S. treasury securities, corporate debt instruments, commercial paper and U.S. government securities with maturities greater than 90 days at date of purchase. Marketable securities with maturities greater than one year are classified as current because management considers all marketable securities to be available for current operations. The Company’s investments have been classified and accounted for as available-for-sale. Such investments are recorded at fair value and unrealized holding gains and losses are reported as a separate component of comprehensive loss in the stockholders’ equity until realized. Realized gains and losses on sales of marketable securities, if any, are determined on the specific identification method and are reclassified from accumulated other comprehensive loss to results of operations as “Other expense, net.” Realized gains and losses were not significant for the years ended December 31, 2023 and 2022, respectively. For the Company’s available-for-sale debt securities in an unrealized loss position, the Company determines whether a credit loss exists. In this assessment, among other factors, the Company considers the extent to which the fair value is less than the amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security. If factors indicate a credit loss exists, an allowance for credit loss will be recorded to “Other expense, net,” limited by the amount that the fair value is less than the amortized cost basis. The amount of fair value change relating to all other factors will be recognized in other comprehensive loss. See Note 2 “Cash, Cash Equivalents and Marketable Securities.” Allowance for Doubtful Accounts The Company maintains an allowance for doubtful accounts for expected credit losses at contract inception resulting from the inability of its customers to make required payments. The Company records a specific allowance and revises the expected loss based on an analysis of individual past-due balances. Additionally, based on historical write-offs and the Company’s collection experience, the Company records an additional allowance based on a percentage of outstanding receivables. The Company performs credit evaluations of its customers’ financial condition. These evaluations require judgment and are based on a variety of factors including, but not limited to, current economic trends, payment history and a financial review of the customer. Actual collection losses may differ from management’s estimates, and such differences could be material to the Company’s financial position and results of operations. Inventory Valuation and Supplier Purchase Commitments Inventory, which primarily consists of finished goods purchased from CMs or ODMs, is stated at the lower of cost (determined by the first-in, first-out method) or market value. Shipments from suppliers before the Company receives them are recorded as in-transit inventory when title and the significant risks and rewards of ownership have passed to the Company. Inbound shipping costs and U.S. tariffs are included in cost of inventory. In addition, from time to time, the Company procures component inventory primarily as a result of manufacturing discontinuation of critical components by suppliers. The Company regularly monitors inventory quantities on hand and records write-downs for excess and obsolete inventories based on the Company’s estimate of demand for its products, potential obsolescence of technology, product life cycles and whether pricing trends or forecasts indicate that the carrying value of inventory exceeds its estimated selling price. The Company also evaluates its supplier purchase commitments, which remain elevated due to the extended lead-times during the global pandemic-induced supply chain challenges, and records a liability for excess and obsolete components based on its estimated demand of our products, potential obsolescence of technology and product life cycles. These factors are impacted by market and economic conditions, competitive dynamics, technology changes and new product introductions and require significant estimates that may include elements that are uncertain. Actual demand may differ from forecasted demand and may have a material effect on gross profit. If inventory is written down, a new cost basis is established that cannot be increased in future periods. For example, during the fourth quarter of 2023, the Company took charges of $28.7 million to write down excess and obsolete inventory and accrue a liability for components at suppliers primarily associated with the Company’s legacy product family that existed before its shift to an all-platform model. During 2023, customers moved to the Company’s platform model at a faster rate than originally anticipated, leaving the Company with excess finished goods and related components at suppliers. Contract Costs The Company capitalizes certain sales commissions related primarily to multi-year cloud-based software subscriptions and extended warranty support contracts. Capitalized commissions are amortized as sales and marketing expenses over the period that the related revenue is recognized, which can be up to five years for extended warranty. The Company classifies the unamortized portion of deferred commissions as current or noncurrent based on the timing of when the Company expects to recognize the expense. The current and noncurrent portions of deferred commissions are included in “Prepaid expenses and other current assets” and “Other assets,” respectively, in the Company’s Consolidated Balance Sheets. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation, and are depreciated using the straight-line method over the estimated useful life of each asset. Generally, computer equipment is depreciated over two years; purchased software is depreciated over three to five years; test equipment is depreciated over three years; furniture and fixtures are depreciated over seven years; and leasehold improvements are depreciated over the shorter of the respective lease term or the estimated useful life of the asset. Maintenance and repairs are charged to expense as incurred. Goodwill Goodwill was recorded as a result of the Company’s acquisitions of Occam Networks, Inc. in February 2011 and Optical Solutions, Inc. in February 2006. The Company records goodwill when consideration paid in a business acquisition exceeds the fair value of the net tangible assets and the identified intangible assets acquired. Goodwill is not amortized but instead is subject to an annual impairment test or more frequently if events or changes in circumstances indicate that it may be impaired. The Company evaluates goodwill on an annual basis as of the end of the second quarter of each fiscal year. Management has determined that it operates as a single reporting unit and, therefore, evaluates goodwill impairment at the enterprise level. At the end of the second quarter of 2023, the Company completed its annual goodwill impairment test. Based on its assessment of certain qualitative factors such as market capitalization, management concluded that the fair value of the Company was more likely than not greater than its carrying amount as of July 2, 2023. As such, it was not necessary to perform the two-step quantitative goodwill impairment test at the time. There have been no significant events or changes in circumstances subsequent to the 2023 annual impairment test that would more likely than not indicate that the carrying value of goodwill may have been impaired as of December 31, 2023. There were no impairment losses for goodwill for the years ended December 31, 2023, 2022 or 2021. Deferred Revenue Deferred revenue results from transactions where the Company billed the customer for products or services and when cash payments are received or due prior to transferring control of the promised goods or services to the customer. Payment terms to customers typically range from net 30 to net 90 days and vary by the size and location of customer and the products or services offered. The period between the transfer of control of the promised good or service to a customer and when payment is due is not significant. Income Taxes The Company evaluates its tax positions and estimates its current tax exposure along with assessing temporary differences that result from different book to tax treatment of items not currently deductible for tax purposes. These differences result in deferred tax assets and liabilities on the Company’s Consolidated Balance Sheets, which are estimated based upon the difference between the financial statement and tax bases of assets and liabilities using the enacted tax rates that will be in effect when these differences reverse. In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in the Company’s Consolidated Statements of Comprehensive Income become deductible expenses under applicable income tax laws or loss or credit carryforwards are utilized. Accordingly, realization of the Company’s deferred tax assets is dependent on future taxable income against which these deductions, losses and credits can be utilized. The Company must assess the likelihood that deferred tax assets will be recovered from future taxable Income, and if the Company determines that recovery is not more likely than not, the Company must establish a valuation allowance. Management judgment is required in determining its provision for income taxes, deferred tax assets and liabilities and any valuation allowance recorded against its net deferred tax assets. Newly Adopted Accounting Standards The Company did not adopt any new accounting standards in 2023 that were significant to the Company. Recent Accounting Pronouncements Not Yet Adopted There have been no accounting pronouncements or changes in accounting pronouncements that are significant or potentially significant to the Company.

Calix, Inc. (together with its subsidiaries, “Calix” or the “Company”) was incorporated in August 1999 and is a Delaware corporation. The Company is the leading global provider of a platform (cloud, software and systems) and managed services that focus on the subscriber-facing network, the portion of the network that governs available bandwidth and determines the range and quality of services that can be offered to subscribers. This platform and managed services enable broadband service providers (“BSPs”) of all sizes to innovate and transform their businesses. The Company’s BSP customers are empowered to utilize real-time data and insights from the Calix platform to simplify their businesses and deliver experiences that excite their subscribers. These insights enable BSPs to grow their businesses through increased subscriber acquisition, loyalty and revenue, thereby increasing the value of their businesses and contributions to their communities.

The accompanying consolidated financial statements have been prepared in accordance with the requirements of the U.S. Securities and Exchange Commission (“SEC”) and U.S. generally accepted accounting principles (“GAAP”). All significant intercompany balances and transactions have been eliminated in consolidation. Any reference in these notes to applicable accounting guidance is meant to refer to the authoritative U.S. GAAP as found in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”).

The preparation of financial statements is in conformity with U.S. GAAP, which requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. For the Company, these estimates include, but are not limited to: allowances for doubtful accounts and sales returns, excess and obsolete inventory, allowances for obligations to its contract manufacturers, valuation of stock-based compensation, useful lives assigned to long-lived assets, standard and extended warranty costs, realizability of deferred tax assets and uncertain tax positions and contingencies. Actual results could differ from those estimates, and such differences could be material to the Company’s financial position and results of operations.

Revenue is recognized when a performance obligation is satisfied, which occurs when control of the promised goods or services is transferred to the customer, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. Revenue from sales of access and premises systems is recognized when control is transferred to the customer, which is generally when the products are shipped. Revenue from software platform licenses, which provides the customer with a right to use the software as it exists, is generally recognized upfront when made available to the customer. Revenue from cloud-based software subscriptions, customer support, maintenance, extended warranty subscriptions and managed services is generally recognized ratably over the contract term. Revenue from professional services and training is recognized as the services are delivered.

A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. The Company’s hardware products contain both software and non-software components that function together to deliver the products’ essential functionality and therefore constitutes a single performance obligation as the promise to transfer the individual software and non-software components is not separately identifiable and, therefore, not distinct. Cloud-based software subscriptions can include multi-year agreements with a fixed annual fee for a minimum committed usage level. To the extent that minimum committed usage level each year varies, the Company has concluded that each year represents a distinct stand-ready performance obligation and the transaction price allocated to each performance obligation is recognized as revenue ratably over each annual period. The Company’s contracts may include multiple performance obligations. For such arrangements, the Company allocates the contract’s transaction price to each performance obligation using the relative stand-alone selling price of each distinct good or service in the contract. The Company generally determines stand-alone selling prices based on the prices charged to customers or its best estimate of stand-alone selling price. The Company’s estimate of stand-alone selling price is established considering multiple factors including, but not limited to, geographies, market conditions, competitive landscape, internal costs, gross margin objectives, characteristics of targeted customers and pricing practices. The determination of estimated stand-alone selling price is made through consultation with and formal approval by management, taking into consideration the go-to-market strategy.

Cost of revenue consists primarily of finished goods inventory purchased from the Company’s contract manufacturers, payroll and related expenses associated with managing the relationships with contract manufacturers, depreciation of manufacturing test equipment, warranty and retrofit costs, excess and obsolete inventory costs, allowances for obligations to its contract manufacturers, shipping charges and amortization of certain intangible assets. It also includes contractor and other costs of services incurred directly related to the delivery of services to customers.

The Company offers limited warranties for its hardware products for a period of one, three or five years, depending on the product type. The Company recognizes estimated costs related to warranty activities as a component of cost of revenue upon product shipment or upon identification of a specific product failure. Under certain circumstances, the Company also provides fixes on specifically identified performance failures for products that are outside of the standard warranty period and recognizes estimated costs related to retrofit activities as a component of cost of revenue upon identification of such product failures. The Company recognizes estimated warranty and retrofit costs when it is probable that a liability has been incurred and the amount of loss is reasonably estimable. The estimates are based upon historical and projected product failure and claim rates, historical costs incurred in correcting product failures and information available related to any specifically identified product failures. Judgment is required in estimating costs associated with warranty and retrofit activities, and the Company's estimates are limited to information available to the Company at the time of such estimates. In some cases, such as when a specific product failure is first identified or a new product is introduced, the Company may initially have limited information and limited historical failure and claim rates upon which to base its estimates, and such estimates may require revision in future periods. The recorded amount is adjusted from time to time for specifically identified warranty and retrofit exposure. Actual warranty and retrofit expenses are charged against the Company’s estimated warranty and retrofit liability when incurred. Factors that affect the Company’s warranty and retrofit liability include the number of active installed units and historical and anticipated rates of warranty and retrofit claims and cost per claim.

Stock-based compensation expense associated with stock options and purchase rights under the Amended and Restated Employee Stock Purchase Plan (the “ESPP”) and the Amended and Restated 2017 Nonqualified Employee Stock Purchase Plan (the “NQ ESPP”) is measured at the grant date based on the fair value of the award and is recognized, net of forfeitures, as expense over the remaining requisite service period (generally the vesting period) on a straight-line basis.

Stock-based compensation expense associated with performance stock options (“PSOs”) with graded vesting features and which contain both a performance and a service condition is measured based on fair value of stock options estimated at the grant date using the Black-Scholes option valuation model, and is recognized, net of forfeitures, as expense over the requisite service period using the graded vesting attribution method.

From time to time, the Company is involved in legal proceedings arising from the normal course of business activities. The Company evaluates the likelihood of an unfavorable outcome of legal proceedings to which it is a party and accrues a loss contingency when the loss is probable and reasonably estimable. Assessing legal contingencies involves significant judgment and estimates, and the outcome of litigation is inherently uncertain and subject to numerous factors outside the Company’s control. Significant judgment is required when the Company assesses the likelihood of any adverse judgments or outcomes, including the potential range of possible losses, and whether losses are probable and reasonably estimable.

Because of uncertainties related to these matters, the Company bases its estimates of whether a loss contingency is probable or reasonably possible, as well as the reasonable range of possible losses associated with each loss contingency, only on the information available at the time. As additional information becomes available, and at least quarterly, the Company reassesses the potential liability on each significant matter and may revise its estimates. These revisions could have a material impact on the Company’s business, operating results or financial condition. The actual outcome of these legal proceedings may materially differ from the Company’s estimates of potential liability, which could have a material adverse effect on the Company’s business, operating results or financial condition.

Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities and accounts receivable. Cash equivalents consist of money market funds and marketable securities with a maturity at the date of purchase of ninety days or less, which are invested through financial institutions in the United States. Deposits in and investments held by these financial institutions may, at times, exceed federally insured limits. The Company has not experienced any losses in such accounts. The Company also has approximately $7.7 million of cash held by its foreign subsidiaries in India, China and the United Kingdom. Management believes that the financial institutions that hold the Company’s cash and cash equivalents are financially sound and, accordingly, minimal credit risk exists with respect to these cash and cash equivalents.

The Company depends primarily on a small number of outside contract manufacturers (“CMs”) and original design manufacturers (“ODMs”) for the bulk of its finished goods inventory. The Company generally purchases its products through purchase orders with its suppliers. While the Company seeks to maintain a sufficient supply of its products, the Company’s business and results of operations could be adversely affected by a stoppage or delay in receiving such products, the receipt of defective parts, an increase in price of such products or the Company’s inability to obtain lower prices from its CMs, ODMs and other suppliers in response to competitive pressures.

The Company has invested its excess cash primarily in money market funds and highly liquid marketable securities such as U.S. treasury securities, corporate debt instruments, commercial paper and U.S. government securities. The Company considers all investments with maturities of three months or less when purchased to be cash equivalents. Marketable securities represent highly liquid U.S. treasury securities, corporate debt instruments, commercial paper and U.S. government securities with maturities greater than 90 days at date of purchase. Marketable securities with maturities greater than one year are classified as current because management considers all marketable securities to be available for current operations.

The Company’s investments have been classified and accounted for as available-for-sale. Such investments are recorded at fair value and unrealized holding gains and losses are reported as a separate component of comprehensive loss in the stockholders’ equity until realized. Realized gains and losses on sales of marketable securities, if any, are determined on the specific identification method and are reclassified from accumulated other comprehensive loss to results of operations as “Other expense, net.” Realized gains and losses were not significant for the years ended December 31, 2023 and 2022, respectively.

For the Company’s available-for-sale debt securities in an unrealized loss position, the Company determines whether a credit loss exists. In this assessment, among other factors, the Company considers the extent to which the fair value is less than the amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security. If factors indicate a credit loss exists, an allowance for credit loss will be recorded to “Other expense, net,” limited by the amount that the fair value is less than the amortized cost basis. The amount of fair value change relating to all other factors will be recognized in other comprehensive loss.

The Company maintains an allowance for doubtful accounts for expected credit losses at contract inception resulting from the inability of its customers to make required payments. The Company records a specific allowance and revises the expected loss based on an analysis of individual past-due balances. Additionally, based on historical write-offs and the Company’s collection experience, the Company records an additional allowance based on a percentage of outstanding receivables. The Company performs credit evaluations of its customers’ financial condition. These evaluations require judgment and are based on a variety of factors including, but not limited to, current economic trends, payment history and a financial review of the customer. Actual collection losses may differ from management’s estimates, and such differences could be material to the Company’s financial position and results of operations.

in-transit inventory when title and the significant risks and rewards of ownership have passed to the Company. Inbound shipping costs and U.S. tariffs are included in cost of inventory. In addition, from time to time, the Company procures component inventory primarily as a result of manufacturing discontinuation of critical components by suppliers. The Company regularly monitors inventory quantities on hand and records write-downs for excess and obsolete inventories based on the Company’s estimate of demand for its products, potential obsolescence of technology, product life cycles and whether pricing trends or forecasts indicate that the carrying value of inventory exceeds its estimated selling price. The Company also evaluates its supplier purchase commitments, which remain elevated due to the extended lead-times during the global pandemic-induced supply chain challenges, and records a liability for excess and obsolete components based on its estimated demand of our products, potential obsolescence of technology and product life cycles. These factors are impacted by market and economic conditions, competitive dynamics, technology changes and new product introductions and require significant estimates that may include elements that are uncertain. Actual demand may differ from forecasted demand and may have a material effect on gross profit. If inventory is written down, a new cost basis is established that cannot be increased in future periods. For example, during the fourth quarter of 2023, the Company took charges of $28.7 million to write down excess and obsolete inventory and accrue a liability for components at suppliers primarily associated with the Company’s legacy product family that existed before its shift to an all-platform model. During 2023, customers moved to the Company’s platform model at a faster rate than originally anticipated, leaving the Company with excess finished goods and related components at suppliers.

Capitalized commissions are amortized as sales and marketing expenses over the period that the related revenue is recognized, which can be up to five years for extended warranty. The Company classifies the unamortized portion of deferred commissions as current or noncurrent based on the timing of when the Company expects to recognize the expense. The current and noncurrent portions of deferred commissions are included in “Prepaid expenses and other current assets” and “Other assets,” respectively, in the Company’s Consolidated Balance Sheets.

Property and equipment are stated at cost, less accumulated depreciation, and are depreciated using the straight-line method over the estimated useful life of each asset. Generally, computer equipment is depreciated over two years; purchased software is depreciated over three to five years; test equipment is depreciated over three years; furniture and fixtures are depreciated over seven years; and leasehold improvements are depreciated over the shorter of the respective lease term or the estimated useful life of the asset. Maintenance and repairs are charged to expense as incurred.

Goodwill was recorded as a result of the Company’s acquisitions of Occam Networks, Inc. in February 2011 and Optical Solutions, Inc. in February 2006. The Company records goodwill when consideration paid in a business acquisition exceeds the fair value of the net tangible assets and the identified intangible assets acquired. Goodwill is not amortized but instead is subject to an annual impairment test or more frequently if events or changes in circumstances indicate that it may be impaired. The Company evaluates goodwill on an annual basis as of the end of the second quarter of each fiscal year. Management has determined that it operates as a single reporting unit and, therefore, evaluates goodwill impairment at the enterprise level.

At the end of the second quarter of 2023, the Company completed its annual goodwill impairment test. Based on its assessment of certain qualitative factors such as market capitalization, management concluded that the fair value of the Company was more likely than not greater than its carrying amount as of July 2, 2023. As such, it was not necessary to perform the two-step quantitative goodwill impairment test at the time.

The Company evaluates its tax positions and estimates its current tax exposure along with assessing temporary differences that result from different book to tax treatment of items not currently deductible for tax purposes. These differences result in deferred tax assets and liabilities on the Company’s Consolidated Balance Sheets, which are estimated based upon the difference between the financial statement and tax bases of assets and liabilities using the enacted tax rates that will be in effect when these differences reverse. In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in the Company’s Consolidated Statements of Comprehensive Income become deductible expenses under applicable income tax laws or loss or credit carryforwards are utilized. Accordingly, realization of the Company’s deferred tax assets is dependent on future taxable income against which these deductions, losses and credits can be utilized.

The Company must assess the likelihood that deferred tax assets will be recovered from future taxable Income, and if the Company determines that recovery is not more likely than not, the Company must establish a valuation allowance. Management judgment is required in determining its provision for income taxes, deferred tax assets and liabilities and any valuation allowance recorded against its net deferred tax assets.