United States

Quarterly Estimated Tax Calculator

Legal basis: IRC §6654 (underpayment of estimated tax); Form 1040-ES (Estimated Tax for Individuals); IRC §6654(d)(1) (required annual payment and safe harbors) · checked 2026-10-04 · Rates and limits change — verify the current figures.

The US income tax system is pay-as-you-go: tax is owed as income is earned, not only when the return is filed in the spring. Employees satisfy this rule through employer withholding, but if you have significant income with no withholding — self-employment profits, investment income, rents, or retirement distributions — you generally must pay estimated tax in four installments during the year using Form 1040-ES. Miss the installments and the IRS charges an underpayment penalty under IRC §6654, calculated as interest on the amount that should have been paid by each due date.

The required annual payment is the smaller of two amounts. The first is 90% of the tax shown on your current-year return. The second is a safe harbor based on the prior year: 100% of the prior year's tax, or 110% if your prior-year adjusted gross income exceeded $150,000 ($75,000 if married filing separately). If your withholding plus timely estimated payments reach that required amount, no penalty applies even if you owe more when you file — you simply pay the balance then. If your income is unpredictable, the prior-year safe harbor is usually the safer target because it is a known number.

The four due dates are not evenly spaced quarters: April 15, June 15, September 15 of the current year, and January 15 of the following year. Each installment covers the income earned since the previous one, which is why the June payment can look small relative to the April one. You may also annualize income on Form 2210 if your earnings were concentrated late in the year, which can reduce or eliminate the penalty.

This calculator takes your expected current-year tax, your withholding, your prior-year tax, and your prior-year AGI band, then applies the safe-harbor structure and splits the remaining amount into four equal installments. The penalty figure is a rough illustration of the §6654 charge, not an exact computation. Thresholds and interest rates change annually, so treat the output as an educational estimate and confirm with the Form 1040-ES instructions or a CPA.

Calculate

Required annual paymentsmaller of $10,800 (90% rule) and $10,000 (prior-year safe harbor)$10,000

Quarterly installmentremaining amount ÷ 4$1,750

Installment due datesfour unequal tax quartersApr 15 · Jun 15 · Sep 15 · Jan 15

Amount covered by withholdingwithholding falls short of the safe harbor$3,000

Estimated underpayment penaltyrough §6654 illustration at the assumed rate; Form 2210 computes the exact amount$280

Balance due at filing (if income estimate holds)no penalty if the safe harbor was met$9,000

How the math works

Required annual payment = the smaller of 90% of the current-year tax, or 100% of the prior-year tax (110% if prior-year AGI exceeded $150,000).
Amount to cover by installments = required annual payment − expected withholding, floored at zero.
Each quarterly installment = remaining amount ÷ 4, due April 15, June 15, September 15, and January 15.
Underpayment penalty (IRC §6654) accrues as interest on each installment that is late or short, from its due date until paid; this tool approximates it with a single annual rate applied to the shortfall.

Frequently asked questions

Who has to pay quarterly estimated taxes?

Generally, individuals who expect to owe at least $1,000 in tax after subtracting withholding and credits. Most W-2 employees are covered by withholding and do not need to make payments; freelancers, landlords, investors, and retirees with insufficient withholding usually do.

What are the safe harbor rules for avoiding the penalty?

Pay (via withholding and timely estimates) the smaller of 90% of the current year's tax or 100% of the prior year's tax — 110% if your prior-year AGI exceeded $150,000. Meet either amount and no underpayment penalty applies, even if you owe more at filing.

When are the quarterly estimated tax due dates?

April 15, June 15, September 15, and January 15 of the following year. When a date falls on a weekend or holiday it shifts to the next business day. The quarters are uneven — the June payment covers only two months of income.

How is the underpayment penalty calculated?

Under IRC §6654 it accrues like interest, separately on each installment from its due date until it is paid, using a rate the IRS sets quarterly. This calculator shows a simplified illustration; Form 2210 computes the actual figure, including the annualized-income method for seasonal businesses.

What if my income is uneven during the year?

You can annualize on Form 2210: compute tax on actual year-to-date income at each due date and pay on what was earned by then. This helps when most income arrives late in the year, but it requires more recordkeeping than four equal payments.

Does withholding count the same as estimated payments?

For penalty purposes withholding is treated as paid evenly throughout the year regardless of when it was actually withheld, which is often more forgiving. Estimated payments count only when actually made, so a large year-end estimate cannot retroactively cure an earlier shortfall.

How do I actually pay?

Mail the Form 1040-ES vouchers with a check, or pay electronically through IRS Direct Pay or EFTPS, selecting 'estimated tax' as the payment type. State estimated payments are separate — most states run their own quarterly schedule.

This calculator is an educational estimate, not tax advice. Safe-harbor percentages, the AGI threshold, and the penalty interest rate are set by law and change periodically, and Form 2210 offers methods this tool does not model. Confirm current-year figures with the IRS Form 1040-ES instructions or a CPA.