MasterTool

Estimated Tax Calculator

Work out safe-harbour estimated payments: the smaller of 90% of this year's tax or 100%/110% of last year's, split into quarters.

IRS estimated-tax safe harbours (Form 1040-ES) last updated · reference source

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Currency: Amounts are calculated in the currency you select; this site does not convert between currencies and does not use live exchange rates.

Dated static reference; no live data is fetched. Verify current source values and assumptions before relying on results.

What this tool does

Computes the smallest estimated payments that avoid an underpayment penalty — the safe harbour. The IRS lets you pay on the lower of two yardsticks: 90% of the current year's tax, or 100% of last year's tax (110% if last year's AGI topped $150,000). Withholding counts toward the target before any quarterly vouchers (Form 1040-ES) are due.

How to use the Estimated Tax Calculator

  1. Enter your figures in the fields above.
  2. Check the filing status, state and pay-frequency selections — they change the tables used.
  3. Read the headline result first, then the breakdown: it shows exactly which tax or amount produced each line.
  4. Change any input to compare scenarios; the result updates with the same dated tables shown on this page.

Formula

required = min(90% × current tax, 100%/110% × prior tax); quarterly = max(0, required − withholding − already paid) ÷ 4
prior tax
Total tax from last year's return (Form 1040), not tax withheld

Worked example

The prior-year harbour is $12,000 (100% of last year's tax), smaller than 90% of this year's expected $14,000 ($12,600); minus $6,000 of withholding leaves $6,000, or $1,500 per quarter.

Inputs

  • Expected total tax for this year14000
  • Expected withholding (W-2 etc.)6000
  • Last year's total tax12000
  • Last year's AGI120000
  • Estimated payments already made0

Result

  • Quarterly estimated payment$1,500.00
  • Required annual payment (safe harbour)$12,000.00
  • Still to pay after withholding and payments$6,000.00
  • Expected balance due at filing$2,000.00

Results explained

Quarterly estimated payment
Each of four equal 1040-ES payments needed to stay inside the safe harbour.
Required annual payment (safe harbour)
The lower of the 90%-of-current and prior-year yardsticks.

Frequently asked questions

Pay at least 90% of this year's tax, or 100% of last year's tax (110% if last year's AGI exceeded $150,000), and you generally owe no underpayment penalty even if you end up owing more.

April 15, June 15, September 15 and the following January 15 (shifted for weekends and holidays). The periods are uneven — Q2 covers two months, Q3 three.

Better, in one way: withholding is treated as paid evenly through the year even if it happens in December, while estimated payments are credited when actually paid. A year-end withholding boost can cure earlier underpayments.

There is generally no underpayment penalty when the balance due after withholding is under $1,000.

Enter your expected total tax (income tax plus self-employment tax) as this year's tax. The Self-Employment Tax Calculator on this site estimates the SE part.