Excess Business Losses: Why a Large Business Loss May Not Be Fully Deductible

The Tax Cuts and Jobs Act introduced a limitation that surprises many business owners who have a large loss year: the excess business loss limitation under IRC §461(l).

In plain English, this rule can stop you from using all of your business loss against other income in the current year.

That does not mean the loss disappears.

It means part of the deduction may be delayed and carried forward.

This is one of the reasons tax planning across years matters. A loss year is not just about the current return. It can also affect future-year tax planning if the carryforward is tracked correctly.

What the Rule Does

The excess business loss limitation applies to noncorporate taxpayers. That includes individuals, trusts, and estates.

It limits how much aggregate trade or business loss can be used in a single year against other income, such as wages, investment income, or other nonbusiness income.

For 2026, the threshold is:

• $256,000 for single filers

• $512,000 for married filing jointly

The general idea is this:

If your total trade or business deductions exceed your total trade or business income and gains by more than the annual threshold, the excess amount is not deductible in the current year.

Instead, the disallowed amount is treated as a Net Operating Loss carryforward.

So the loss is not necessarily gone.

It is delayed.

A Simple Example

Suppose you are married filing jointly.

You have $200,000 in wages, and your business produces a $700,000 operating loss.

For 2026, the married-filing-jointly excess business loss threshold is $512,000.

That means the excess business loss calculation produces a $188,000 disallowed amount — the part of the $700,000 business loss that exceeds the $512,000 threshold.

The $188,000 is not deducted in the current year.

Instead, it is treated as a Net Operating Loss carryforward and may reduce taxable income in a future year, subject to the NOL rules.

You may still be able to use $512,000 of the business loss currently, assuming the loss clears the other applicable limitation rules.

That last part matters.

How It Affects S-Corp and Partnership Owners

Business losses from S-Corps and partnerships flow through to owners on Schedule K-1.

But once the loss reaches the owner, it still has to be tested at the individual level.

If you own interests in multiple pass-through entities, the calculation looks at your aggregate trade or business income and losses. That means income from one business may offset losses from another business before the excess business loss limitation applies.

For example, if one partnership passes through a $100,000 business gain and another S-Corp passes through a $400,000 business loss, those items do not get analyzed in isolation. They are part of the broader owner-level calculation.

This is why pass-through loss planning is not just about one K-1.

It is about the full return.

The Loss Limitation Stack Matters

The excess business loss rule is not the only limitation that can affect a pass-through loss.

Before a loss becomes currently deductible, it may also have to clear:

• Basis limitations

• At-risk rules

• Passive activity loss rules

• The excess business loss limitation

For S-Corp and partnership owners, this matters because a K-1 loss is not automatically deductible just because it appears on the K-1.

A loss might be suspended because the owner does not have enough basis.

It might be limited because the owner is not economically at risk.

It might be passive and only usable against passive income.

Or it might clear those rules and still be limited by the excess business loss threshold.

The practical point is simple:

You need to know where the loss stopped.

That determines how it is tracked and when it may become usable.

The NOL Carryforward

When a loss is disallowed under the excess business loss rule, it is treated as a Net Operating Loss carryforward.

That carryforward may reduce taxable income in a later year, subject to the NOL rules.

For post-2017 NOLs, the deduction is generally limited to 80% of taxable income in the year the carryforward is used. That means even when the loss moves into a future year, it may not wipe out all taxable income at once.

It still has value.

But it has to be tracked.

If you had a significant business loss year and no one has discussed an NOL carryforward with you, that is a gap worth addressing.

Final Thought

A large business loss does not always mean a large current-year deduction.

That is the part many business owners miss.

The tax return may show a real business loss, but the Code may limit how much of that loss can be used right now.

The rest may carry forward.

This is not about losing the deduction.

It is about timing, tracking, and making sure the carryforward does not disappear because no one maintained the schedule.

A loss year still matters.

You just need to know whether the benefit is available now, later, or not until another limitation is resolved.