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Estimated Tax Safe Harbor Calculator (90, 100 and 110 Percent)

What does this come to under the current IRS rules?

Required annual payment, quarterly installments and due dates from current-year tax, prior-year tax and prior-year AGI.

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  • Nothing stored or sent
  • Free, no sign-up
Your figures
Example figuresIllustrative only. Type over them with your own.
Required annual payment (smaller)
$54,000
Pay at least this to meet the safe harbor
90% of current-year tax
$54,000
Prior-year tax x 110%
$57,200
Drawn to one scale
90% of current-year tax$54,000
Prior-year tax x 110%$57,200
Required annual payment (smaller)$54,000
Still to pay through installments$34,000
Each of four installments$8,500
All results
MeasureResult
90% of current-year tax$54,000
Prior-year tax x 110%$57,200
Required annual payment (smaller)$54,000
Still to pay through installments$34,000
Each of four installments
Due Apr 15, Jun 15, Sep 15 2026 and Jan 15 2027
$8,500
How this was worked out
Work shownrecomputed as you type
Required annual payment = smaller of 90% x current tax and (100% or 110%) x prior tax
110% applies when prior AGI > $150,000 ($75,000 if married filing separately)
Installment = (required - withholding) / 4

Illustrative arithmetic on the figures you enter. Check the result against your firm's methodology before relying on it.

The formulas

  • Required annual payment = smaller of 90% x current tax and (100% or 110%) x prior tax
  • 110% applies when prior AGI > $150,000 ($75,000 if married filing separately)
  • Installment = (required - withholding) / 4

How it works

Tax year: 2026.

The required annual payment is the smaller of 90 percent of the current-year tax and 100 percent of the prior-year tax. The prior-year figure becomes 110 percent when prior-year AGI was more than $150,000 ($75,000 if married filing separately). No estimated payment is required when the tax after withholding and refundable credits is under $1,000.

The 2026 installments are due April 15, June 15 and September 15, 2026 and January 15, 2027, per the IRS estimated tax schedule for 2026. The tool divides the unpaid required amount into four equal installments. Annualized income installments are not modeled.

Illustrative figures only. Check the result against your firm's methodology before relying on it.

Common questions

What is the 110 percent rule?

If your prior-year AGI was above $150,000 ($75,000 if married filing separately), the prior-year safe harbor is 110 percent of that year's tax, not 100 percent.

Which test sets the amount?

The smaller of the 90 percent current-year amount and the prior-year amount.

When is a payment not needed?

When the tax owed after withholding and refundable credits is less than $1,000.

Sources

Runs in your browser. The figures you type are not sent to CORAA or stored. Check the result against your firm's methodology before relying on it.

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