Accounting for deferred income taxes under U.S. GAAP means comparing the book value of every asset and liability on your balance sheet against its tax basis, recording a deferred tax asset or liability for each difference expected to reverse in a future period, and measuring those balances at the enacted tax rate expected to apply when the reversal happens. The governing standard is ASC Topic 740. The federal corporate tax rate remains 21% for 2026, and the One Big Beautiful Bill Act signed on July 4, 2025 changed enough of the underlying tax rules — bonus depreciation and research expensing in particular — that many companies had to remeasure existing deferred balances in the period of enactment.
Temporary Differences Versus Permanent Differences
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 matters: the gap will eventually close, and when it does the company will either owe more tax or get a tax deduction. Both outcomes need to show up on the balance sheet today, even though the cash hits later.
Taxable temporary differences create deferred tax liabilities. The classic case is depreciation. A company might depreciate equipment over ten years on its books but deduct the full cost immediately on its tax return. The tax basis drops to zero while the book value stays high, so future book depreciation will exceed future tax depreciation and produce taxable income with no matching tax deduction. The liability reflects the tax the company will eventually owe.
Deductible temporary differences run the other way and create deferred tax assets. A warranty reserve is the textbook example. The company accrues an estimated liability on its books when it sells a product, but tax law doesn’t allow the deduction until the warranty claim is paid. The future payment generates a tax deduction the company hasn’t yet received.
Permanent differences never reverse and never create deferred taxes. Tax-exempt municipal bond interest is income on the books but never taxable. Government fines are an expense on the books but never deductible. Entertainment expenses face the same treatment. These items affect the company’s effective tax rate but produce no deferred balance because there’s no future reversal to account for.
Where Deferred Balances Come From
Depreciation and amortization generate the largest temporary differences for most companies. The One Big Beautiful Bill Act permanently restored 100% first-year bonus depreciation for qualified property acquired after January 19, 2025.1Internal Revenue Service. Treasury, IRS Issue Guidance on the Additional First Year Depreciation Deduction Amended as Part of the One Big Beautiful Bill 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. That produces a large taxable temporary difference in year one and a deferred tax liability that unwinds over the remaining book depreciation period.
Research and development costs took an unusual 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. That created a significant deductible temporary difference for companies expensing R&D on their books. The One Big Beautiful Bill Act reversed the capitalization rule for tax years beginning after December 31, 2024, allowing 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 must still be capitalized and amortized over 15 years.3Internal Revenue Service. Rev. Proc. 2025-28
Other common sources include bad debt reserves accrued on the books but deductible only when written off for tax, stock-based compensation where the book expense follows vesting but the tax deduction depends on exercise, revenue recognized at different times for book and tax, and lease liabilities under ASC 842 where the right-of-use asset and lease liability have no tax basis. Each produces either a deferred tax asset or liability depending on which direction the book-tax gap runs.
Measuring the Balances
The measurement rule is simple to state: multiply each temporary difference by the enacted tax rate expected to apply when it reverses. Enacted is the key word. You cannot use proposed rates, expected rates, or rates in active legislation. Only rates signed into law count.
For a company operating only at the federal 21% rate, 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 a temporary difference reverse in years with different enacted rates. That exercise, called scheduling, requires applying each year’s enacted rate to the amount reversing in that year. If a 25% rate were enacted starting in 2028, a company with temporary differences reversing both before and after would apply 21% to pre-2028 reversals and 25% to post-2028 reversals.
State income taxes add another layer. Most states impose their own corporate tax at rates ranging from zero to roughly 11.5%, and each state is a separate jurisdiction for deferred tax purposes. The state deferred balance is calculated using each state’s enacted rate net of the federal benefit from deducting state taxes, and tracked separately from the federal balance.
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 is only worth something if the company will actually 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, meaning a greater than 50% chance the benefit will not materialize.
The assessment weighs all available positive and negative evidence. A three-year cumulative pre-tax loss is treated as significant negative evidence that is hard to overcome. Other negative evidence includes a history of unused tax benefits expiring, expected future losses, and unsettled circumstances that could hurt future profitability. Positive evidence includes a strong earnings history, a firm backlog of orders or contracts, appreciated asset values that would generate taxable gains if sold, and existing taxable temporary differences whose reversal will generate income the deferred tax asset can offset.
Management evaluates four specific sources of future taxable income when deciding whether a deferred tax asset is realizable:
- Reversals of existing taxable temporary differences. Deferred tax liabilities already on the books will produce taxable income on reversal that can absorb the deferred tax asset.
- Future taxable income from operations. Projected earnings based on budgets and forecasts, though these carry less weight when negative evidence is present.
- Carryback to prior years. Under current federal law this is largely unavailable, but it still matters in states that allow carrybacks and for certain farming losses at the federal level.
- Tax-planning strategies. Actions management would take to prevent a benefit from expiring, such as accelerating income recognition, converting ordinary losses to capital character, or switching from tax-exempt to taxable investments.
When the evidence tips against realization, the company debits income tax expense and credits the valuation allowance. That increases the tax provision on the income statement without any cash changing hands. If circumstances improve later, the allowance is reversed through a credit to income tax expense. This is where most restatement risk lives in practice, because small changes in the assessment can swing reported earnings by millions, and auditors scrutinize these judgments heavily.
Net Operating Loss Carryforwards
When tax deductions exceed taxable income, the result is a net operating loss. The loss carries forward to reduce taxable income in future years, which makes it a deferred tax asset measured at the enacted rate and subjected to the same valuation allowance test as any other.
Two rules from the Tax Cuts and Jobs Act of 2017 remain in effect for 2026. NOLs arising in tax years ending after 2017 can generally be carried forward indefinitely, with no 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% cap means a company with a large carryforward cannot wipe out its entire tax bill in a single profitable year, which complicates both scheduling and the valuation allowance assessment.
Carrybacks are eliminated for NOLs arising after 2020, with one notable federal exception: farming losses still qualify for a two-year carryback. A farming loss equals the smaller of the company’s total NOL or the NOL calculated using only farming income and deductions.5Internal Revenue Service. Instructions for Form 172 State rules vary widely. Some states conform to the federal indefinite carryforward, while others impose their own time limits, often 20 years. Multistate companies track NOL carryforwards by jurisdiction.
For a company with a history of cumulative losses, the NOL deferred tax asset is the most scrutinized item on the balance sheet. The indefinite carryforward helps because the benefit technically never expires, but the 80% annual cap means sustained profitability is needed to fully absorb the loss. Management must present credible, verifiable evidence of future taxable income, and outside auditors will challenge projections that aren’t grounded in identifiable revenue sources.
Uncertain Tax Positions
Not every position on a tax return is a sure thing. When a company claims a deduction, exclusion, or credit that might not survive an audit, ASC 740 requires a two-step evaluation before any tax benefit can appear in the financial statements.6FASB. Summary of Interpretation No. 48
The first step is recognition. Judged purely on its technical merits, is the 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 on.
The second step is measurement. The company calculates the largest dollar amount of benefit with a greater than 50% chance of being realized on settlement. That involves assigning probabilities to each possible outcome and working from the most favorable outcome downward until the cumulative probability exceeds 50%. The amount at that point is recognized; any excess is recorded as an unrecognized tax benefit liability. That liability is not classified as a deferred tax liability unless it arises from a taxable temporary difference.
Companies have an accounting policy choice for interest and penalties on uncertain positions. Interest can be reported as either income tax expense or interest expense, and penalties can be classified as either income tax expense or another operating expense. The election must be applied consistently once made, and the interest policy can differ from the penalty policy.
Remeasuring When the Law Changes
When a new tax law is enacted, companies must adjust their deferred tax balances in the period of enactment, even if the provisions don’t take effect until a future year. Any deferred balance expected to reverse after the new rules kick in gets remeasured at the new enacted rate or under the new rules. The adjustment flows through income tax expense.
The One Big Beautiful Bill Act, signed July 4, 2025, triggered exactly this kind of remeasurement. Two provisions did most of the work.
Permanent restoration of 100% bonus depreciation for qualified property acquired after January 19, 2025 meant companies that had been building deferred tax liabilities on the phasing-down schedule — which would have dropped to 40% for 2026 and 20% for 2027 under prior law — needed to remeasure. Those liabilities likely increased because full expensing accelerates more taxable income into the future reversal period.
Restoration of immediate R&D expensing for domestic research cut the other way. Companies capitalizing R&D over five years under the original TCJA rule carried deferred tax assets reflecting future amortization deductions they hadn’t yet claimed. Once immediate deduction returned, those future deductions largely disappeared and the related deferred tax assets had to be written down, which increased income tax expense in the period of enactment.
A Note on Business Combinations
Acquisitions produce their own deferred tax mechanics that don’t follow the ordinary rules above. The buyer records the target’s assets and liabilities at fair value for book purposes while tax basis usually stays put, creating fresh temporary differences recognized on the acquisition date. The most common result is a deferred tax liability for intangibles like customer relationships or technology, offset by an increase to goodwill rather than a charge to income tax expense. The acquirer also reassesses the target’s existing deferred tax assets and any needed valuation allowance against the combined entity’s prospects. Measurement-period adjustments based on conditions existing at acquisition hit goodwill; later changes or post-acquisition events hit income tax expense.
Balance Sheet and Income Statement Presentation
All deferred tax assets and liabilities are classified as noncurrent on the balance sheet, regardless of when the underlying temporary difference is expected to reverse. ASU 2015-17 eliminated the old requirement to split deferred taxes between current and noncurrent.7FASB. Income Taxes (Topic 740) Balance Sheet Classification of Deferred Taxes
Within a single tax jurisdiction and tax-paying entity, deferred tax assets and liabilities are netted. A company with a $200,000 federal deferred tax asset and a $350,000 federal deferred tax liability reports a net noncurrent deferred tax liability of $150,000. Deferred taxes from different jurisdictions cannot be combined; a net federal deferred tax liability and a net state deferred tax asset in a different jurisdiction appear separately.
The income statement shows two components. Current tax expense is the actual tax payable or refundable for the period. Deferred tax expense is the net change in deferred tax asset and liability balances during the period. Together they make up the total income tax provision. The deferred component can be negative if deferred tax assets grew or deferred tax liabilities shrank during the year, reducing the overall 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 statutory federal rate to the 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. For a U.S.-domiciled company at 21% that means any item exceeding roughly 1.05% of pre-tax income from continuing operations requires separate disclosure.8FASB. Improvements to Income Tax Disclosures