Net Loss vs. Net Operating Loss: Conversion, Limits, and Carryforward

A net loss and a net operating loss describe the same bad year from two different angles. The net loss is what your books show when expenses beat income. The net operating loss, or NOL, is what the tax code lets you actually carry into future years after stripping personal and nonbusiness items out of that accounting figure. Understanding the difference between a net loss and a net operating loss matters because you can’t drop your accounting loss onto a tax return and expect the IRS to honor it; the number that survives the Section 172 modifications is almost always smaller.

What Each Number Actually Is

A net loss is the raw accounting figure. Add up everything the business brought in, subtract cost of goods sold, then subtract operating costs like rent, payroll, and utilities. If the result is negative, that’s your net loss. It shows up on your profit and loss statement and tells you how the year went financially.

A net operating loss is the tax version of that figure, and it’s almost always a different number. The IRS requires you to modify the accounting loss by removing deductions that don’t relate to actual business operations. What remains is the amount you’re allowed to carry forward against future income. The modifications under Internal Revenue Code Section 172 are what make the conversion official.¹

Turning a Net Loss Into a Net Operating Loss

The starting point is the excess of your allowable deductions over gross income for the year. From there, Section 172 forces several adjustments that keep personal financial choices from inflating the business loss.

For individual taxpayers, the biggest adjustments are these:

Nonbusiness deductions can only offset nonbusiness income. If you have $5,000 in investment income and $12,000 in personal deductions, only $5,000 of those deductions count. The extra $7,000 can’t inflate your NOL.
Capital losses can only offset capital gains. A capital loss doesn’t get to increase your NOL even if the loss feels very real.
The qualified business income deduction under Section 199A must be added back when computing the NOL for tax years through 2025. The Section 199A deduction expired at the end of 2025 and does not apply to 2026 tax years unless Congress renews it.

The point of these rules is to keep the NOL reflecting genuine operating losses from business activity, not a stack of personal deductions and investment setbacks dressed up as a business problem.¹

How You Use the NOL Once You Have It

The Tax Cuts and Jobs Act rewrote how NOLs work for losses arising in tax years beginning after December 31, 2017. Two changes matter most. Carrybacks disappeared for most taxpayers, and the deduction is now capped at 80% of taxable income in any carryforward year.²

The 80% cap means a carried-forward loss can’t fully zero out your tax bill. Say your business earns $200,000 this year and you’re carrying a $300,000 NOL. You can deduct $160,000 (80% of $200,000). You owe tax on the remaining $40,000, and the unused $140,000 rolls to the next year.

The trade-off is that post-2017 losses never expire. Under the old rules, an NOL had to be used within 20 years or it was gone. Now the deduction is smaller each year but keeps rolling until it’s fully absorbed.³

Ordering When Multiple Years Stack Up

When you’re carrying NOLs from more than one year, the oldest loss goes first. The entire loss from the earliest year gets used before any portion of a later year’s loss is touched. The carryforward for each year is whatever remains after subtracting the taxable income of each prior year the loss was applied against.¹

Losses From Before 2018

If you’re still carrying an NOL from a tax year that began before January 1, 2018, different rules apply to that vintage. Those losses have a 20-year expiration window and are not subject to the 80% cap. In a year where you have both pre-2018 and post-2017 NOLs, the pre-2018 losses go first and can offset up to 100% of taxable income. The 80% limitation only applies to the post-2017 portion.¹

Losses That Never Become Part of Your NOL

Not every dollar of red ink feeds into a net operating loss. Two limitations catch taxpayers who assume all losses are equal.

Passive Activity Losses

If you own a business but don’t materially participate in running it, your losses from that activity are passive. Passive losses can only offset passive income, not wages, active business profits, or investment returns. Disallowed passive losses don’t fold into your NOL. They’re suspended and carried forward inside the passive activity system until you either generate passive income or dispose of the entire interest.⁴

The Excess Business Loss Cap

Even when you actively run the business, Section 461(l) caps how much business loss noncorporate taxpayers can use against nonbusiness income like wages, interest, and capital gains. For 2025, the threshold was $313,000 for single filers and $626,000 for joint filers, adjusted annually for inflation. The limitation applies through 2028.

The portion of your loss above the threshold isn’t destroyed. It converts to an NOL carryforward for the next tax year and follows the standard carryforward rules from that point.⁵

If Your Business Is a Pass-Through

S corporations and partnerships don’t carry NOLs at the entity level. Losses pass through to the shareholders and partners, who report them on their personal returns. Once a loss flows to you, it becomes your personal NOL and is subject to the same rules already described: the 80% limit, the excess business loss cap, and the Section 172 modifications.

Before you can deduct an S corp loss, you need enough stock and debt basis in the company. Partnerships have similar basis requirements. If your share of the loss exceeds your basis, the excess is suspended until your basis increases. Basis limitations apply before passive activity and excess business loss rules, so losses can get blocked at multiple levels before any NOL question is even reached.

Carrybacks Are the Exception, Not the Rule

Most taxpayers lost the ability to carry losses to prior years after the TCJA. Farming businesses can still carry farming losses back two years, calculated using only income and deductions from the farming operation. Any amount left after offsetting the two prior years carries forward indefinitely under the normal rules.¹ Non-life insurance companies retain a two-year carryback and a 20-year carryforward.⁶ If neither of those describes you, your only option is carrying the loss forward.

Forms That Make the Distinction Real

The place where net loss and NOL split apart on paper is Form 172. Individuals, estates, and trusts use it to compute the actual NOL available for carryback or carryforward, working through the Section 172 modifications step by step. The form was introduced in late 2024. Sole proprietors also need Schedule C to report the underlying business income or loss that feeds the calculation.³⁷

Using an NOL carryforward on your annual return is simpler than the calculation that produced it. On Form 1040, the deduction goes on Schedule 1, line 8a, as a negative number reducing your other income. You don’t file anything to “register” the loss for future use. Each year until the loss is absorbed, you compute the available NOL on Form 172 and enter the deductible portion on your return.⁸

Records Have to Outlast the Loss

Because post-2017 NOLs carry forward indefinitely, recordkeeping stretches well past the usual three-year window. Keep supporting documentation for any year that generated an NOL until three years after you fully use the carryforward or three years after it expires. A $500,000 loss generated in 2024 that takes until 2031 to absorb means holding 2024 records until at least 2034.³

That means keeping the original return from the loss year, the Form 172 calculation, receipts and ledger entries supporting each deduction, and records showing how much of the NOL was applied in each subsequent year. The IRS does ask for this documentation years later, and reconstructing a loss calculation from a decade back without records is effectively impossible.⁹

1
Office of the Law Revision Counsel. 26 USC 172 – Net Operating Loss Deduction
2
Internal Revenue Service. Tax Cuts and Jobs Act: A Comparison for Businesses
3
Internal Revenue Service. Instructions for Form 172
4
Internal Revenue Service. Passive Activity and At-Risk Rules
5
Internal Revenue Service. Instructions for Form 461
6
Internal Revenue Service. Instructions for Form 1139
7
Internal Revenue Service. About Schedule C (Form 1040), Profit or Loss from Business (Sole Proprietorship)
8
Internal Revenue Service. 2025 Instructions for Form 1040
9
Internal Revenue Service. How Long Should I Keep Records