Accounting for deferred income taxes under U.S. GAAP means recording today the future tax consequences of transactions your financial statements have already recognized. ASC Topic 740 governs the work: you compare the book carrying value of each asset and liability against its tax basis, identify the temporary differences, multiply each by the enacted tax rate expected when it reverses, and post the result as either a deferred tax asset or a deferred tax liability. Deferred tax assets then get a second look through a valuation allowance if their realization is in doubt. The federal corporate rate stays at 21% for 2026, but the One Big Beautiful Bill Act signed on July 4, 2025 changed the underlying tax rules enough that many companies had to remeasure balances they had carried for years.
Temporary Differences: The Core of Deferred Tax
A temporary difference is the gap between what your financial statements say an asset or liability is worth and what your tax return says it’s worth. The word “temporary” carries the whole idea. The gap will eventually close, and when it does the company will either owe more tax or get a tax deduction. Both outcomes have to appear on today’s balance sheet, even though the cash effect comes later.
Taxable temporary differences create deferred tax liabilities. Depreciation is the standard example. A company might depreciate equipment over ten years on the books but deduct the full cost immediately for tax purposes. Tax basis falls to zero while book value stays high. Future book depreciation will exceed future tax depreciation, producing taxable income with no offsetting deduction. The deferred tax liability captures the tax the company will owe when that reversal happens.
Deductible temporary differences run the other way and create deferred tax assets. A warranty reserve is the classic case. The company accrues the estimated liability on its books at the time of sale, but the tax deduction waits until the warranty claim is paid. Book basis exceeds tax basis, and the future payment produces a tax deduction the company has not yet received.
Permanent differences are a separate category and never create deferred taxes. Municipal bond interest is income on the books but never taxable. Government fines and certain entertainment expenses are book expenses but never deductible. These items affect the effective tax rate for the year they occur but produce nothing to defer because there is no future reversal.
Common Sources of Temporary Differences
Depreciation and amortization produce the largest temporary differences at most companies. The One Big Beautiful Bill Act permanently restored 100% first-year bonus depreciation for qualified property acquired after January 19, 2025, so a company buying equipment in 2026 deducts the full cost for tax purposes immediately while spreading the expense over the asset’s useful life on its books.1Internal Revenue Service. Treasury, IRS Issue Guidance on the Additional First Year Depreciation Deduction Amended as Part of the One Big Beautiful Bill Full year-one expensing creates a large taxable temporary difference and a matching deferred tax liability that unwinds over the remaining book depreciation period.
Research and development took a strange path. The Tax Cuts and Jobs Act of 2017 required companies to capitalize domestic R&D and amortize it over five years for tax purposes starting in 2022, producing a large deductible temporary difference for anyone still expensing R&D on the books. The One Big Beautiful Bill Act reversed this for tax years beginning after December 31, 2024, restoring immediate deduction of domestic R&D or an elective amortization over at least 60 months.2Internal Revenue Service. One, Big, Beautiful Bill Provisions Foreign R&D still has to be capitalized and amortized over 15 years.3Internal Revenue Service. Rev. Proc. 2025-28
Other frequent temporary differences include bad debt reserves, which are accrued on the books but deductible only when specific accounts are written off; stock-based compensation, where the book expense follows vesting and the tax deduction depends on exercise; revenue recognized on different schedules for book and tax; and lease liabilities and right-of-use assets under ASC 842, which typically have no tax basis at all. Each of these creates either a deferred tax asset or a deferred tax liability depending on which direction the book-tax gap runs.
Measuring the Deferred Tax Asset or Liability
The measurement rule is simple to state. Multiply each temporary difference by the enacted tax rate expected to apply when the difference reverses. “Enacted” is the word to watch. Proposed rates, expected rates, and rates in pending legislation do not count. Only rates signed into law. When a new law is enacted, deferred tax balances get remeasured in that same reporting period, even if the rate change takes effect years later.
For a company operating only in the federal jurisdiction at 21%, a $1,000,000 taxable temporary difference produces a $210,000 deferred tax liability. A $300,000 deductible temporary difference produces a $63,000 deferred tax asset. The math gets more involved when portions of the difference reverse in years with different enacted rates. That process, called scheduling, requires applying each year’s enacted rate to the portion reversing in that year.
State income taxes add another layer. Most states impose their own corporate tax at rates from zero up to roughly 11.5%, and each state is a separate jurisdiction for deferred tax purposes. A multistate company calculates state deferred taxes using each state’s enacted rate net of the federal benefit from deducting state taxes and tracks each jurisdiction separately from the federal calculation.
Within a single jurisdiction, ASC 740 requires netting. A company with a $105,000 federal deferred tax liability and a $63,000 federal deferred tax asset reports a single net federal deferred tax liability of $42,000. A federal deferred tax asset cannot be netted against a state deferred tax liability, because they belong to different taxing jurisdictions.
The Valuation Allowance on Deferred Tax Assets
A deferred tax asset only has value if the company will earn enough taxable income to use it. ASC 740 requires a valuation allowance against any deferred tax asset that is more likely than not to go unrealized. “More likely than not” means a greater than 50% chance the benefit will not materialize.
The judgment rests on weighing all available positive and negative evidence. A three-year cumulative pre-tax loss counts as significant negative evidence that is hard to overcome. Other negative evidence includes a history of tax benefits expiring unused, expected future losses, and unsettled circumstances that could hurt future profitability. Positive evidence includes a strong earnings history, a firm backlog of orders, appreciated asset values that would generate taxable gains on sale, and existing taxable temporary differences whose future reversal will generate income the deferred tax asset can offset.
Management evaluates four sources of future taxable income when deciding whether a deferred tax asset is realizable:
- Reversals of existing taxable temporary differences already sitting on the balance sheet as deferred tax liabilities.
- Future taxable income from operations, based on budgets and forecasts, though projections carry less weight when significant negative evidence exists.
- Carrybacks to prior years, which are largely unavailable under current federal law but still matter in states that permit them and for federal farming losses.
- Tax-planning strategies management would use to keep a benefit from expiring, such as accelerating income, converting ordinary losses to capital character, or shifting from tax-exempt to taxable investments.
When the evidence tips against realization, the entry debits income tax expense and credits the valuation allowance. Reported tax expense rises without any cash moving. If circumstances later improve, the allowance is reversed through a credit to income tax expense. Most restatement risk in tax accounting lives here in practice, because small changes in the assessment can swing reported earnings by millions, and auditors scrutinize the judgment closely.
Net Operating Loss Carryforwards
When deductions exceed taxable income, the result is a net operating loss. That loss can offset taxable income in future years, so it sits on the balance sheet as a deferred tax asset. The NOL carryforward is measured at the enacted rate and gets the same valuation allowance treatment as any other deferred tax asset.
The Tax Cuts and Jobs Act changed two things about NOLs that still hold for 2026. NOLs arising in tax years ending after 2017 can generally be carried forward indefinitely, eliminating the old 20-year expiration clock. And the NOL deduction in any given year is capped at 80% of taxable income.4Internal Revenue Service. Tax Cuts and Jobs Act: A Comparison for Businesses The 80% limit means a company with a large NOL carryforward cannot wipe out its entire tax bill in a single profitable year, which complicates both scheduling and the valuation allowance assessment.
Carrybacks are generally not allowed for NOLs arising after 2020, with one federal exception. Farming losses still qualify for a two-year carryback.5Internal Revenue Service. Instructions for Form 172 A farming loss is the smaller of the total NOL or the NOL calculated using only farming income and deductions. State rules vary. Some states follow the federal indefinite carryforward, others impose their own limits (often 20 years), so multistate companies track carryforwards jurisdiction by jurisdiction.
For a company with a track record of losses, the NOL deferred tax asset is the most scrutinized line on the balance sheet. Indefinite carryforward helps because the benefit does not expire, but the 80% annual cap means the company needs sustained profitability to fully absorb the loss. Management has to present credible, verifiable evidence of future taxable income sufficient to use the carryforward, and outside auditors will challenge projections not grounded in identifiable revenue.
Uncertain Tax Positions
Not every position on a tax return will survive audit. When a company claims a deduction, exclusion, or credit that might be challenged, ASC 740 requires a two-step evaluation before any tax benefit is recognized in the financial statements.6FASB. Summary of Interpretation No. 48
Step one is recognition. Judged purely on its technical merits, is the tax position more likely than not to be sustained if the taxing authority examines it with full knowledge of all relevant facts? If no, the benefit is not recognized at all. If yes, the position moves to measurement.
Step two is measurement. The company calculates the largest amount of benefit that has a greater than 50% chance of being realized on settlement. Probabilities get assigned to each possible outcome, and the calculation works from the most favorable outcome downward until cumulative probability exceeds 50%. The amount at that point is what gets recognized. Any excess between the position taken on the return and the amount recognized in the financials is recorded as an unrecognized tax benefit liability, which is not classified as a deferred tax liability unless it arises from a taxable temporary difference.
Companies also make an accounting policy choice about interest and penalties on uncertain positions. Interest can be reported as either income tax expense or interest expense. Penalties can be reported as either income tax expense or another operating expense. The elections must be applied consistently, and the interest policy can differ from the penalty policy.
Remeasuring When Tax Law Changes
When a new tax law is enacted, deferred tax assets and liabilities must be adjusted in the enactment period, even if the substantive rules do not take effect until a future year. Any balance expected to reverse under the new rules gets remeasured at the new enacted rate or under the new provisions, and the adjustment flows through income tax expense.
The One Big Beautiful Bill Act, signed on July 4, 2025, forced this kind of remeasurement across two areas.
Permanent restoration of 100% bonus depreciation for qualified property acquired after January 19, 2025 required companies to redo deferred tax liability calculations that had assumed the old phase-down (40% for 2026 and 20% for 2027 under prior law).1Internal Revenue Service. Treasury, IRS Issue Guidance on the Additional First Year Depreciation Deduction Amended as Part of the One Big Beautiful Bill Companies whose deferred tax liabilities were built on partial bonus depreciation typically saw those balances increase, because full expensing pushes more taxable income into future reversal periods.
The R&D provision worked the other direction. Companies capitalizing R&D over five years under the original TCJA rule carried deferred tax assets reflecting future amortization deductions they had not yet claimed. Once immediate deduction of domestic R&D was restored, most of those future deductions disappeared, so the related deferred tax assets had to be written down.2Internal Revenue Service. One, Big, Beautiful Bill Provisions The write-down increased income tax expense in the period of enactment.
Presentation and Disclosure
All deferred tax assets and liabilities are classified as noncurrent on the balance sheet, whatever the timing of the underlying reversal. That rule came in with ASU 2015-17, which eliminated the old split between current and noncurrent deferred taxes.7FASB. Income Taxes (Topic 740) Balance Sheet Classification of Deferred Taxes
Within a single jurisdiction and single tax-paying entity, deferred tax assets and liabilities are netted to a single amount. A company with a $200,000 federal deferred tax asset and a $350,000 federal deferred tax liability reports a $150,000 net noncurrent deferred tax liability. Balances from different jurisdictions cannot be combined, so a company with a net federal liability and a net state asset presents both separately.
On the income statement, income tax expense has two components: current tax expense (the amount actually payable or refundable for the period) and deferred tax expense (the net change in deferred tax asset and liability balances during the year). Together they make up the total tax provision. The deferred component can be negative when deferred tax assets grow or deferred tax liabilities shrink, pulling total tax expense below the current cash obligation.
Footnote disclosures under ASC 740 are extensive. Companies disclose the gross amounts of all deferred tax assets and liabilities by type, the total valuation allowance, and a reconciliation of the federal statutory rate to the company’s effective tax rate. Under ASU 2023-09, public companies must disaggregate the rate reconciliation into eight specific categories, including state and local taxes, foreign tax effects, enacted law changes, cross-border tax effects, tax credits, valuation allowance changes, nontaxable or nondeductible items, and changes in unrecognized tax benefits. Any single reconciling item whose effect exceeds 5% of the statutory tax amount must be broken out further, which for a U.S.-domiciled company at 21% means any item exceeding roughly 1.05% of pre-tax income from continuing operations requires separate disclosure.8FASB. Improvements to Income Tax Disclosures