Your Business Had a Loss. Here's How the IRS Lets You Use It — and Where It Stops.

If your business deductions exceed your income for the year, you have a net operating loss — an NOL. The IRS doesn’t make you pay tax on money you didn’t make. What they do is let you carry that loss forward to offset income in future profitable years.

Most business owners know that much. What they don’t know is the 80% cap. And that cap changes your tax planning in ways that catch people off guard.

How you end up with an NOL

A net operating loss is simpler than it sounds. Take your business income. Subtract your allowable deductions. If the number is negative, you have an NOL equal to the shortfall.

This happens more often than you’d expect. Startup years, bad revenue years, large capital investments that generate big deductions — any of these can push your numbers below zero.

The most common one I’m seeing right now: 100% bonus depreciation. With permanent 100% bonus depreciation now on the books (more on how that works here), a business owner can buy $250,000 of equipment in December and deduct the full amount in year one. If their net income before that deduction was $180,000, they now have a $70,000 NOL. On paper, they lost $70,000. In reality, they bought equipment and got a deduction. The NOL is the leftover.

The rules changed in 2018 — and most owners don’t know it

Before 2018, the NOL rules worked like this: carry the loss back two years (get a refund check from the IRS), or carry it forward up to 20 years and fully offset income dollar for dollar.

Starting in 2018, the rules changed significantly and have stayed that way.

No carryback (for most businesses). You can no longer send the loss back to prior years and get a refund. The loss goes forward.

Unlimited carryforward period. The 20-year cap is gone. An NOL generated in 2026 can theoretically be carried forward forever. It does not expire.

80% of taxable income limit. In any given year, you can only use your NOL to offset up to 80% of your taxable income. Not 100%. The remaining 20% is still taxable. Whatever NOL you don’t use continues to carry forward to the following year.

That 80% cap is the piece that surprises people.

What the 80% cap means in practice

Here’s a concrete example. You generate a $200,000 NOL in year one — maybe it was a difficult startup year, maybe you bought a lot of equipment.

Year two, your business rebounds. Net income of $250,000. You have $200,000 of NOL sitting there. How much of that can you use?

The cap: 80% of $250,000 = $200,000. Your NOL is exactly $200,000. You use all of it, and your taxable income is $50,000. You pay tax on $50,000. NOL fully used. That worked out.

Now change one number: the NOL is $250,000 and year two income is $250,000.

80% of $250,000 = $200,000 maximum offset. You have $250,000 of NOL but can only use $200,000. Taxable income is $50,000. Remaining NOL: $50,000, carried to year three.

The surprise: even with more NOL than income, you still owe tax on 20% of your year two income. Many business owners expect a profitable year after a loss to be tax-free. It’s not.

The estimated tax trap

Here’s where it gets operationally dangerous. If you had a big loss last year and you’re having a good year now, you might assume you don’t need to make quarterly estimated payments — or that you need very small ones. You figure the NOL will cover it.

It won’t cover all of it. That 20% floor is taxable income. And if you underpay your quarterly estimates, the IRS charges a penalty — regardless of whether you have an NOL carryforward. The NOL doesn’t excuse late estimated payments. It just reduces the eventual tax bill.

I’ve seen business owners get blindsided by this. They had a rough prior year, they’re back to profitability, they’re making money and feeling good — and in April they owe a meaningful tax bill plus an underpayment penalty. The penalty isn’t huge, but the bill itself is larger than they expected. Plan for it.

More on the estimated tax penalty and how it’s calculated here.

Timing and planning around NOLs

If you know you’re going to generate an NOL this year, a few things are worth thinking through.

Consider the source. If your NOL comes from a large equipment purchase (bonus depreciation), you chose to accelerate that deduction into the current year. That’s often right — but not always. If your income this year is lower than your projected income next year, the deduction is worth more next year. Timing the purchase into January instead of December could change the math significantly.

Model the carryforward. The NOL is valuable, but it’s not a dollar-for-dollar reduction in tax owed. Think of it as a 80%-efficient tool. A $100,000 NOL reduces your taxable income in a future year by up to $80,000 per year until it’s used up. Size your projections accordingly.

Don’t double-count it. If you’re calculating estimated payments for a year when you expect to use NOL carryforwards, use the 80% rule — don’t assume you’ll owe nothing. Your taxable income after the NOL offset is still taxable.

One more layer: the excess business loss limit

There’s a separate rule that limits how much business loss you can deduct in the year it’s generated. If your losses are large enough to exceed a certain annual threshold — this applies to individual returns, not corporate returns — the amount over the limit doesn’t flow through as a current-year deduction. It’s converted into an NOL that you carry forward.

This rule has its own inflation adjustments each year. The concept is: there’s a cap on how much business loss can offset your other income (like a spouse’s W-2) in any single year. If your business loss exceeds that cap, the excess becomes an NOL. It’s not lost, but it’s deferred.

If you’re generating losses that are large relative to your other income, this is worth understanding before year-end so there are no surprises at filing.

The bottom line

An NOL is a legitimate tax tool. It softens the blow of a bad year and helps fund the recovery. But it doesn’t eliminate your tax liability in future years — it reduces it by up to 80% per year, with the rest carrying forward indefinitely.

If you’re sitting on NOL carryforwards heading into a profitable year, two things matter: adjusting your quarterly estimated payments to account for the 20% you’ll still owe, and having a clear picture of how many years it’ll take to burn through the carryforward at your projected income levels. That’s the kind of forward projection we build into business tax preparation — planning, not guessing.

This post is for general informational purposes only and does not constitute tax advice. Net operating loss rules are complex and depend on your specific entity type, income, and circumstances. Tax laws change. Consult a qualified tax professional before making decisions based on this content.