# Safe harbor estimated tax rules for 2026: the 90%, 100% and 110% tests that avoid the penalty

Source: https://taxbracketsdesk.com/estimated-taxes/estimated-tax-safe-harbor
Publisher: Tax Brackets Desk (taxbracketsdesk.com), independent editorial site
Topic: Estimated Taxes
Last updated: 2026-10-20

> To meet the 2026 safe harbor for estimated tax and avoid the IRS underpayment penalty, your withholding plus on-time estimated payments must equal the smaller of 90% of your 2026 tax or 100% of your 2025 tax. If your 2025 AGI was over $150,000 ($75,000 married filing separately), the prior-year figure is 110%. The last 2026 payment is due January 15, 2027.

## Key facts

- Current-year test: 90% of 2026 tax (66 2/3% for farmers and fishers)
- Prior-year test: 100% of 2025 tax
- High-income prior-year test: 110% if 2025 AGI over $150,000 ($75,000 MFS)
- Small-balance test: Under $1,000 owed after withholding and refundable credits
- Withholding timing: Treated as paid one-fourth on each due date unless you elect actual dates

## What is the safe harbor for estimated taxes?

A safe harbor for estimated tax is a payment target that, if met on time, means you owe no underpayment penalty, even if you still owe a balance when you file. For tax year 2026 the target, which Form 1040-ES calls the required annual payment, is the smaller of 90% of your 2026 tax or 100% of the tax on your 2025 return.

The safe harbor does not reduce your tax. It only decides whether a penalty applies. Anything above the safe harbor amount is simply paid with your return by the April 2027 deadline, with no penalty attached.

## The three tests that keep you penalty-free

You avoid the underpayment penalty for 2026 if any one of these is true (Pub. 505 and IRS Topic 306):

1. **The $1,000 test:** you owe less than $1,000 after subtracting withholding and refundable credits.
2. **The current-year test:** withholding plus timely estimated payments equal at least 90% of your 2026 tax.
3. **The prior-year test:** withholding plus timely estimated payments equal at least 100% of the tax on your 2025 return, which must cover a full 12 months, or 110% if your 2025 AGI was over $150,000.

There is also a no-liability exception: if you had zero total tax for a full 2025 tax year and were a U.S. citizen or resident alien all year, you do not need to make 2026 estimated payments at all.

The tests apply per installment, not only for the full year. Roughly one-quarter of the required annual payment must be in by each of the four [2026 due dates](https://taxbracketsdesk.com/estimated-taxes/estimated-tax-due-dates): April 15, June 15 and September 15, 2026, and January 15, 2027. Meeting the target by paying everything in January still leaves penalties for April, June and September.

## When do I need to pay 110% of last year's tax?

You need the 110% safe harbor if the AGI on your 2025 return, Form 1040 line 11b, was more than $150,000, or more than $75,000 if your 2026 filing status is married filing separately (2026 Form 1040-ES). It replaces the 100% prior-year test only; the 90% current-year test stays the same.

The trigger is last year's AGI, not this year's. Someone whose AGI fell from $170,000 in 2025 to $90,000 in 2026 still uses 110%; someone who jumped from $120,000 to $400,000 uses 100%. The rule does not apply if at least two-thirds of your 2025 or 2026 gross income came from farming or fishing.

## Example: choosing the cheapest safe harbor estimated tax payments

Suppose a single filer had 2025 AGI of $180,000 and total tax of $30,000. In 2026 a consulting side business pushes expected tax to $42,000. Their employer will withhold $20,000 of income tax during 2026.

| Test | Calculation | Target |
| --- | --- | --- |
| 90% of 2026 tax | $42,000 x 90% | $37,800 |
| 110% of 2025 tax | $30,000 x 110% | $33,000 |
| Required annual payment | Smaller of the two | $33,000 |
| Less expected withholding | $33,000 - $20,000 | $13,000 |
| Each quarterly payment | $13,000 / 4 | $3,250 |

Comparing the two safe harbor tests (illustrative figures)

The remaining $9,000 of 2026 tax ($42,000 minus $33,000) is due with the return in April 2027, with no underpayment penalty. Had this person's 2025 AGI been $150,000 or less with the same $30,000 of tax, the target would drop to $30,000, or $2,500 per quarter.

When income is rising, the prior-year safe harbor is nearly always the smaller number. When income is falling, 90% of the lower current-year tax can win, but it requires an accurate forecast, because underestimating 2026 tax can leave you short.

## Does withholding count toward the safe harbor?

Yes, and it counts more flexibly than estimated payments. The Instructions for Form 2210 treat federal income tax withheld during the year as paid in equal quarters on the four due dates, unless you elect to use the dates it was actually withheld.

That makes withholding a catch-up tool. If you missed the April and June payments, raising withholding for the rest of the year on a new Form W-4 spreads that extra tax back across all four periods. Our [Form W-4 withholding guide](https://taxbracketsdesk.com/payroll-tax/w-4-withholding-guide) covers the extra-withholding line, and a year-end bonus withheld at the flat [bonus tax rate](https://taxbracketsdesk.com/payroll-tax/bonus-tax-rate) helps the same way.

Line 13 of the Form 1040-ES worksheet includes all expected income tax withholding, including Additional Medicare Tax withheld by an employer and excess Social Security tax when two or more employers paid you more than $184,500 in total wages.

## Prior year safe harbor when your filing status changes

The 2026 worksheet instructions cover two common changes. If you will file jointly for 2026 but filed separately for 2025, add the two 2025 taxes together. If you filed jointly for 2025 but will file separately for 2026, you split the 2025 joint tax in proportion to what each spouse would have owed on a separate return.

If you did not file a 2025 return, or your 2025 tax year was shorter than 12 months, you cannot use the prior-year test. Your only safe harbor is 90% of 2026 tax, or keeping the balance under $1,000.

## Does the safe harbor apply to state estimated taxes?

States set their own rules, and some differ sharply. California uses the same 90%, 100% and 110% tests but a $500 threshold ($250 married/RDP filing separately), and taxpayers with 2026 California AGI of $1,000,000 or more ($500,000 married/RDP filing separately) cannot use the prior-year test at all (2026 Form 540-ES instructions).

Check your own state's estimated tax instructions each year. The federal prior-year safe harbor does not protect you from a state penalty.

## Putting the safe harbor into your 2026 and 2027 plans

The Form 1040-ES worksheet runs this comparison on lines 12a to 12c; our [Form 1040-ES walkthrough](https://taxbracketsdesk.com/estimated-taxes/form-1040-es-instructions) shows each line. For 2027, your 2026 return becomes the prior-year figure, and the payment schedule is on our [estimated tax due dates 2027](https://taxbracketsdesk.com/estimated-taxes/estimated-tax-due-dates-2027) page. The rest of the process is in our [estimated taxes guide](https://taxbracketsdesk.com/estimated-taxes). If you already missed a 2026 payment, our [estimated tax penalty](https://taxbracketsdesk.com/estimated-taxes/estimated-tax-penalty) page shows how the charge is figured and how to limit it.

## Common questions

### If I meet the safe harbor, will I still owe money in April?

You can. The safe harbor only removes the underpayment penalty. Any tax above what you prepaid is still due with your return, but no penalty is added if you pay it by the filing deadline.

### Is the 110% safe harbor based on 2025 or 2026 AGI?

It is based on the AGI shown on your 2025 return. If that was over $150,000 ($75,000 if married filing separately for 2026), use 110% of your 2025 tax for the 2026 prior-year test.

### Does a refund applied from last year count toward the safe harbor?

Yes. An overpayment from your 2025 return that you credit to 2026 estimated tax counts as a payment made April 15, 2026, if the 2025 return was filed on time.

### What counts as last year's tax for the safe harbor?

Generally the total tax on your 2025 Form 1040 line 24, minus certain items such as refundable credits (for example the earned income credit and additional child tax credit) and some Schedule 2 taxes listed in the Form 1040-ES instructions.

### Can I use the safe harbor if I did not file last year?

No. The prior-year test needs a 2025 return covering 12 months. Without one, you must prepay 90% of your 2026 tax, unless you had no tax liability in 2025.

## Sources

- [Form 1040-ES (2026), Estimated Tax for Individuals](https://www.irs.gov/pub/irs-pdf/f1040es.pdf)
- [Publication 505 (2026), Tax Withholding and Estimated Tax](https://www.irs.gov/pub/irs-pdf/p505.pdf)
- [Instructions for Form 2210](https://www.irs.gov/pub/irs-pdf/i2210.pdf)
- [Topic 306, Penalty for underpayment of estimated tax](https://www.irs.gov/taxtopics/tc306)
- [2026 Instructions for Form 540-ES (California FTB)](https://www.ftb.ca.gov/forms/2026/2026-540-es-instructions.html)