Safe Harbor Estimated Tax Calculator 2026

Find the smallest amount you can pay the IRS during 2026 and still avoid the underpayment penalty. Enter your projected 2026 tax, your 2025 return and what you have paid so far to see what is left for each due date.

Your numbers

Projected 2026 total tax after credits, including self-employment tax2026 federal income tax withheld (W-2, pensions, etc.)2025 total tax (leave blank if you had no 2025 return)2025 adjusted gross income (AGI)Filing statusDid your 2025 return cover all 12 months?Did you file a 2025 return?Estimated payment 1: dateEstimated payment 1: amountEstimated payment 2: dateEstimated payment 2: amountEstimated payment 3: dateEstimated payment 3: amountEstimated payment 4: dateEstimated payment 4: amount

List the 2026 estimated payments you have made (or plan to make) with the date of each. A 2025 refund applied to 2026 counts as a payment dated Apr 15, 2026.

Enter yearly amounts in US dollars. Results update as you type and never leave your browser.

Not tax advice. This calculator gives educational estimates based on 2026 federal rules published by the IRS and SSA. It ignores state taxes and many credits and special situations. Check with a tax professional or the IRS before filing or paying.
Last reviewed: November 1, 2026.

How we calculate it

The safe harbor is the minimum you must pay during the year, through withholding and on-time estimated payments, to avoid the IRS underpayment penalty. We compute it the way Form 2210 does:

$1,000 test. If your 2026 tax minus withholding is under $1,000, no estimated payments are required.
Required annual payment = the lower of 90% of your 2026 tax or 100% of your 2025 tax. If your 2025 AGI was over $150,000 ($75,000 if married filing separately), the prior-year figure is 110% of your 2025 tax. AGI of exactly $150,000 uses 100%.
The 2025 option needs a real 2025 return: it must cover a full 12 months and you must have filed it. Otherwise only the 90% option is available. If your 2025 tax was $0 on such a return, 100% of it is $0.
Installments. 25% of the required annual payment is due by each date: April 15, June 15 and September 15, 2026, and January 15, 2027.
Credits. Withholding counts as paid in four equal parts on the due dates (you can elect to use the actual dates on Form 2210; we assume even spreading). Each estimated payment counts on the date you made it and goes first to the earliest installment that is still short.
Still to pay for each date = 25% − what was credited to that installment. A part covered after its due date is shown as late, because the penalty is figured installment by installment.

Your 2026 tax is a projection, so the 90% target moves with it; the 100%/110% target is fixed once your 2025 return is filed. Not covered: the annualized income installment method (Schedule AI), special rules for farmers and fishermen, penalty waivers and state estimated taxes.

Worked example

Single filer. Projected 2026 tax $20,000 and $2,000 of W-2 withholding. 2025 return: 12 months, filed, total tax $14,000, AGI $90,000 (not over $150,000, so 100% applies). Estimated payments: $3,000 each on Apr 15, Jun 15 and Sep 15, 2026.

Step	Amount
90% × $20,000	$18,000
100% × $14,000	$14,000
Required annual payment (lower)	$14,000
Needed by each due date (25%)	$3,500
Apr 15, Jun 15, Sep 15: $500 withholding + $3,000 paid	$3,500 each, on time
Jan 15, 2027: $3,500 − $500 withholding	$3,000 still to pay

Paying $3,000 by January 15, 2027 meets the safe harbor ($2,000 + $12,000 = $14,000). The other $6,000 of 2026 tax is still due with the 2026 return, but without an underpayment penalty.

Same person with 2025 AGI of $160,000: the prior-year figure becomes 110% × $14,000 = $15,400, or $3,850 per date. Each payment first catches up the earliest short installment, so the shortfall on time grows: $350 on Apr 15, $700 on Jun 15 and $1,050 on Sep 15. That leaves $4,400 still to pay: $550 for Sep 15 (after the $500 of January withholding) and $3,850 for Jan 15. A small penalty can already apply to the late parts.

Estimated tax penalty calculator: what missing the safe harbor costs, day by day
1099 quarterly estimated tax calculator: project your 2026 tax
Self-employment tax calculator: the SE tax part of your 2026 total tax
Guide: the January 15, 2027 estimated tax payment

FAQ

What is the safe harbor for 2026 estimated taxes?

You avoid the underpayment penalty if your withholding and on-time estimated payments cover the lower of 90% of your 2026 tax or 100% of your 2025 tax (110% if your 2025 AGI was over $150,000, or $75,000 married filing separately), paid in four equal parts by each due date.

When does the 110% rule apply?

When the AGI on your 2025 return was more than $150,000, or more than $75,000 if you are married filing separately. At exactly $150,000 the 100% rule still applies.

Do I need estimated payments if I owe less than $1,000?

No. If your 2026 tax minus withholding is under $1,000, there is no underpayment penalty, so no estimated payments are required.

What if I had no tax in 2025 or did not file?

If your 2025 return covered 12 months, you filed it and it showed $0 of tax, 100% of $0 is $0, so no estimated payments are required. If you did not file a 2025 return or it covered less than 12 months, only the 90%-of-2026 option is available.

Does withholding count toward the safe harbor?

Yes. Withholding is treated as paid in four equal parts on the due dates, even if it was taken late in the year, unless you elect to use the actual dates on Form 2210.

Can I skip the January 15, 2027 payment?

Only that one: if you file your 2026 return and pay all the tax by February 1, 2027 (January 31 is a Sunday), the January 15 installment has no penalty. The first three still count.

Sources

Last reviewed November 1, 2026 by the Self Employed Math editorial team against the sources above.