When your deductions and business losses exceed your gross income for the year, you have negative taxable income. That doesn’t just zero out your tax bill. The excess generally becomes a net operating loss (NOL) you can carry forward indefinitely to reduce taxable income in future years, though the carryforward can only offset up to 80% of any single year’s income.1Office of the Law Revision Counsel. 26 USC 172 – Net Operating Loss Deduction The negative number on your return, though, is rarely the number you get to carry. Several adjustments and loss-limitation rules usually shrink it first.
When Taxable Income Actually Goes Negative
Taxable income equals gross income minus deductions. Gross income covers wages, investment earnings, business revenue, and most other money coming in. From that you subtract either the standard deduction or itemized deductions, plus above-the-line adjustments like retirement contributions.2Internal Revenue Service. Instructions for Form 1040
For most wage earners, taxable income doesn’t drop below zero. It happens when large business losses swamp everything else on the return. A sole proprietor filing Schedule C, a partner in an LLC, or someone with significant rental real estate losses can generate deductions that outstrip wages, dividends, and other income combined. A new restaurant that loses $200,000 in its first year while the owner earns $80,000 in outside wages would produce roughly negative $120,000 in taxable income before any further adjustments.
Why the Negative Number Isn’t Your NOL
IRC Section 172(d) requires you to strip out items unrelated to a trade or business before you land on the loss amount that actually carries forward.1Office of the Law Revision Counsel. 26 USC 172 – Net Operating Loss Deduction The IRS uses Form 172 for the calculation.3Internal Revenue Service. Instructions for Form 172
The main adjustments add back items that shouldn’t inflate a business-driven loss:
- Non-business deductions can only reduce your NOL to the extent they’re covered by non-business income. Your standard deduction or most itemized deductions, IRA contributions, HSA deductions, and similar personal deductions get limited to your interest, dividends, and other non-business income. If non-business income is $5,000 but your standard deduction is $15,000, only $5,000 of that deduction survives into the NOL calculation.
- Net capital losses can only offset capital gains for NOL purposes. The $3,000 annual deduction for net capital losses against ordinary income is added back.
- Any qualified business income deduction claimed under Section 199A is reversed.
- Any excluded gain from qualified small business stock under Section 1202 is added back.
- Prior NOL deductions can’t be stacked to enlarge the current year’s loss.
The result is often meaningfully smaller than the negative figure on your return. Someone showing $100,000 of negative taxable income might end up with a $60,000 NOL after adding back personal deductions that exceeded their investment income.4Internal Revenue Service. Instructions for Form 172
Three Loss Filters That Apply First
Before a business loss can even reach the NOL calculation, it has to survive three sequential filters. Each can suspend or cap part of your loss, and they apply in a fixed order. A loss caught by an earlier filter never makes it to the next one.
At-Risk Rules
The first filter limits your deductible loss in an activity to the amount you have at risk, which is essentially cash you’ve invested plus amounts you’ve personally borrowed and are liable for. Non-recourse loans where you have no personal liability generally don’t count. Any loss above your at-risk basis is suspended until you put more money into the activity. You calculate this on Form 6198, and suspended amounts carry forward indefinitely.5Office of the Law Revision Counsel. 26 USC 465 – Deductions Limited to Amount at Risk
Passive Activity Loss Rules
Losses that clear the at-risk filter face the passive activity rules next. Losses from rental properties and businesses where you don’t materially participate can only offset passive income.6Internal Revenue Service. Publication 925 Excess passive losses are suspended and carry forward until you generate enough passive income or sell the entire activity.
One exception matters for many landlords: if you actively participate in rental real estate and your modified adjusted gross income is below $100,000, you can deduct up to $25,000 of rental losses against non-passive income like wages. That allowance phases out between $100,000 and $150,000 of MAGI and disappears above $150,000.6Internal Revenue Service. Publication 925
Excess Business Loss Limitation
The last filter caps how much total business loss a non-corporate taxpayer can deduct in one year. For 2026 the threshold is $256,000 for single filers and $512,000 for married couples filing jointly.7Internal Revenue Service. Rev. Proc. 2025-32 Business losses over that cap don’t vanish; they convert automatically into an NOL carryforward.8Internal Revenue Service. Excess Business Losses
Because this limitation applies after the at-risk and passive activity rules have done their work, only losses that cleared both earlier hurdles count against the excess business loss cap.9Internal Revenue Service. Instructions for Form 461
How the Carryforward Works
Once you’ve calculated the NOL on Form 172, it carries forward with no expiration date. The old two-year carryback was eliminated for most taxpayers starting with losses arising after 2020.1Office of the Law Revision Counsel. 26 USC 172 – Net Operating Loss Deduction
The 80% rule is the main constraint. In any future year you use an NOL arising after 2017, the deduction can only offset 80% of that year’s taxable income calculated before the NOL itself. Earn $100,000 with a $100,000 NOL waiting, and you can use $80,000 of it. Tax is owed on the remaining $20,000, and the unused $20,000 of NOL keeps carrying.1Office of the Law Revision Counsel. 26 USC 172 – Net Operating Loss Deduction A large NOL can take several years to fully absorb because that 20% slice of each year’s income is always taxable, no matter how big your carryforward balance.
Farmers get a narrow exception: farming losses from tax years beginning after 2020 can still be carried back two years to generate refunds of previously paid tax, or the carryback can be waived by the return’s due date, including extensions.1Office of the Law Revision Counsel. 26 USC 172 – Net Operating Loss Deduction
How to Claim It
For the year the loss occurs, you compute the NOL on Form 172 and keep it with your records.3Internal Revenue Service. Instructions for Form 172 When you carry the NOL forward, report the deduction as a negative number on Schedule 1 (Form 1040), line 8a, and attach a statement to that return showing how you computed the NOL deduction, including the original loss and any amounts absorbed in earlier years.
The Self-Employment Tax Trap
An NOL reduces income tax but has no effect on self-employment tax. IRC Section 1402(a)(4) specifically excludes the NOL deduction from the calculation of net earnings from self-employment.10Office of the Law Revision Counsel. 26 USC 1402 – Definitions Even if a carryforward wipes out your entire income tax liability, you still owe the 15.3% self-employment tax on whatever you earned from your business that year. Planning around an NOL without accounting for this can produce an unexpected bill.
What Happens on Death or Divorce
An unused NOL carryforward can be claimed on the decedent’s final income tax return, and if the surviving spouse files a joint return for the year of death, the NOL can offset income on that return. Any carryforward not absorbed by the final return is gone. It does not transfer to the estate.11Internal Revenue Service. Publication 559 – Survivors, Executors, and Administrators This is one of the few ways an NOL simply evaporates, which makes income timing in the final year worth some attention.
When spouses who filed jointly generated an NOL together and later divorce, the loss has to be split. Each spouse’s share is proportional to what they would have reported on a hypothetical separate return. If only one spouse’s income and deductions created the loss, the entire NOL belongs to that spouse.3Internal Revenue Service. Instructions for Form 172
Keep Records for as Long as the NOL Lives
The IRS can examine any year in which you claim an NOL deduction, and without substantiation of the original loss the entire deduction can be disallowed. Copies of tax returns alone are not sufficient proof, and neither are an accountant’s workpapers or general testimony about what happened.12Internal Revenue Service. IRM 4.11.11 Net Operating Loss Cases
Keep the original return that generated the NOL, all supporting schedules, the Form 172 calculation, and the underlying financial documents for at least three years after the loss is fully used up. Because NOLs now carry forward indefinitely, that effectively means holding those records for as long as any balance remains, plus three more years. A loss generated in 2026 that isn’t fully absorbed until 2035 means keeping records through at least 2038.
State Rules Often Diverge
Federal NOL rules don’t automatically apply at the state level. Some states match the 80% federal limitation, others cap the deduction at a lower percentage or fixed dollar figure, and a few have temporarily suspended NOL deductions for higher-income taxpayers. Carryback availability and carryforward periods also vary. If you operate in multiple states or moved during the carryforward period, check each state’s current rules before assuming the federal number is what you get.