Quarterly Estimated Tax Calculator
Estimates your quarterly federal estimated-tax payment by applying your expected effective tax rate to expected annual income and dividing into four equal installments. Designed for the self-employed, contractors, retirees, and anyone with significant non-wage income that does not have tax withheld at source.
Last updated: May 2026
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About this calculator
The formula is quarterly payment = (expectedIncome × estimatedTaxRate ÷ 100) ÷ 4. This treats the year as four equal periods and assumes a flat effective rate, which is an approximation. The US estimated-tax system actually uses unequal quarters — Q1 covers Jan 1–Mar 31 (due April 15), Q2 covers Apr 1–May 31 (due June 15), Q3 covers Jun 1–Aug 31 (due Sept 15), Q4 covers Sept 1–Dec 31 (due Jan 15 of the next year) — so the "quarters" are 3, 2, 3, and 4 months long, but each takes 25% of expected annual tax under the flat method. For irregular income, the Annualized Income Installment method (Form 2210 Schedule AI) lets you pay more in quarters when income is higher and less in lighter quarters; this calculator does not implement that and will overpay or underpay in any given quarter for irregular-income filers. The rate you enter should reflect everything you owe — federal income tax (effective rate, NOT marginal — see income-tax FAQ), Social Security 12.4% and Medicare 2.9% on net self-employment earnings up to the wage base, the 0.9% Additional Medicare surcharge above the threshold, NIIT at 3.8% on net investment income above $200k/$250k MAGI, and any state estimated tax (though state is usually a separate payment). For a self-employed person at moderate income, the effective combined rate is often 25–35%. Safe Harbor: paying 100% of last year's total tax (110% if AGI exceeded $150,000) split across four quarters guarantees no underpayment penalty regardless of how much you actually earn this year — many filers use last year's tax bill divided by four as their default estimated-tax payment. Edge cases: a rate of 0% returns 0 (you might still owe — the formula just gives zero); a very high rate (>50%) overstates; entering only expected income and no rate would give zero, so both fields must be reasonable.
How to use
Example 1 — Self-employed designer, steady income. You expect to earn $80,000 net from your design business in 2024. Your combined effective rate (federal income tax ~12% effective on ~$72k of taxable income after SE-tax deduction and standard deduction, plus 15.3% SE tax on $80k × 92.35% ≈ $11,303 SE tax, plus minor state) is roughly 30%. Enter expectedIncome = 80000, estimatedTaxRate = 30. Result: $6,000 per quarter (×4 = $24,000 annual). Verify: 80000 × 0.30 / 4 = 6000 ✓. Pay this via IRS Direct Pay or EFTPS by April 15, June 15, September 15, and January 15. If you have a W-2 spouse, their withholding counts toward Safe Harbor, so you may be able to reduce these estimates. Example 2 — Retiree with IRA distributions and dividends. You are taking a $120,000 traditional IRA distribution plus $30,000 in qualified dividends and long-term capital gains for a total income of $150,000. Federal income tax effective rate is roughly 15% on the IRA (ordinary income brackets) plus 15% on the qualified gains (long-term capital gains bracket) — combined effective ~15%. Enter expectedIncome = 150000, estimatedTaxRate = 15. Result: $5,625 per quarter (×4 = $22,500 annual). Verify: 150000 × 0.15 / 4 = 5625 ✓. Alternative: ask the IRA custodian to withhold federal tax at 20% on each distribution and skip estimated payments entirely — withholding counts as paid evenly through the year for Safe Harbor purposes, which is often simpler than four separate IRS payments.
Frequently asked questions
Who is required to make estimated tax payments?
Any individual who expects to owe at least $1,000 in federal tax after withholding and refundable credits for the current year, AND who did not have at least 90% of current-year tax (or 100%/110% of last-year tax under Safe Harbor) paid through withholding. In practice this includes: independent contractors and freelancers (1099-NEC income), gig workers (rideshare, delivery), small-business owners (Schedule C, partnership K-1s, S-corp K-1s), real estate landlords with rental income, retirees with no withholding on IRA distributions or pensions, investors with large dividend/interest/capital-gains income, and people with significant non-wage income alongside a W-2. C-corporations have their own quarterly estimated tax regime (Form 1120-W). The penalty for not making estimates when required is the same underpayment penalty discussed under tax-refund — daily interest at the federal short-term rate plus 3 percentage points (about 8% annualized in 2024), computed per quarter. The IRS does not bill estimated tax automatically; you must self-assess and remit. Farmers and fishermen earning two-thirds of gross income from those activities have a special rule allowing a single annual estimated payment by January 15.
What is Safe Harbor and how do I use it?
Safe Harbor is a set of three IRS rules that, if met, eliminate the underpayment penalty regardless of your actual liability. The three doors are: (1) Your total tax due after withholding is less than $1,000. (2) You paid at least 90% of current-year tax through withholding and timely estimated payments. (3) You paid at least 100% of last year's total tax (or 110% if last year's AGI exceeded $150,000 — $75,000 if married filing separately). The 100%/110% prior-year safe harbor is the simplest: take last year's Form 1040 line 24 (Total tax), multiply by 1.10 if your prior AGI was >$150k or 1.00 otherwise, divide by four, and pay that amount each quarter. This shields you from penalty even if your income spikes mid-year and you actually owe much more (you settle up at filing time but with no penalty). Caution: if last year was unusually low income (e.g., a sabbatical or business loss), the prior-year safe harbor may be too small to cover most of this year's bill, leaving a big April balance even if no penalty — plan cash flow accordingly.
When are the four quarterly payments due?
For tax year 2024: Q1 due April 15, 2024 (covering Jan 1–Mar 31); Q2 due June 17, 2024 (covering Apr 1–May 31, the 15th is a Saturday so it shifts); Q3 due September 16, 2024 (covering Jun 1–Aug 31, the 15th is a Sunday so it shifts); Q4 due January 15, 2025 (covering Sept 1–Dec 31). Note the unequal periods — Q2 is only two months, Q4 is four months. Payments can be made via IRS Direct Pay (direct bank transfer, no fee), EFTPS (Electronic Federal Tax Payment System, also free), debit/credit card (fees apply, processed by third-party vendors), or paper check with Form 1040-ES voucher (slow, easy to misroute). Direct Pay is generally the easiest for individual filers. State estimated taxes have their own deadlines and payment systems and must be tracked separately. If a due date falls on a weekend or federal holiday, the deadline shifts to the next business day. Late payments accrue penalty interest until the next quarter's payment or filing, whichever comes first.
Common mistakes with estimated tax?
First, forgetting Self-Employment tax — a 1099 contractor making $60k owes ~$8,500 in SE tax on top of income tax, so a rate that only reflects the income-tax bracket dramatically underpays. Second, ignoring half-of-SE-tax deduction — the deductible employer-equivalent SE-tax portion reduces income-tax liability, so the effective combined rate is lower than (income-tax rate + 15.3%). Third, missing a quarter — the IRS calculates underpayment penalty per quarter, so even if your annual total is right, missing Q1 incurs a Q1 penalty. Fourth, treating estimated tax as a year-end true-up — IRS expects payments roughly aligned to when income is earned, not lumped into Q4. Fifth, ignoring W-2 withholding — if you also have a W-2 (or a spouse does), that withholding counts toward Safe Harbor and may reduce or eliminate the estimated-tax requirement. Sixth, ignoring state estimated tax — many states require parallel quarterly payments with their own deadlines and penalty regimes. Seventh, not adjusting mid-year when income changes materially — the IRS expects you to revise estimates as conditions change.
When should I not use this calculator?
Skip it if your income is highly irregular — a seasonal business with all income in Q3 should use the Annualized Income Installment Method (Form 2210 Schedule AI) rather than equal quarters, which can significantly reduce early-quarter payments. Skip it for W-2-only employees with no side income; just adjust your W-4 withholding instead, which is administratively simpler and counts as paid evenly through the year. Skip it for the year of a major windfall (RSU vest, business sale, IPO, large capital gain) — the prior-year Safe Harbor often makes estimates dramatically simpler than guessing at current-year tax; just pay 100%/110% of last year's total tax in four equal chunks and settle up in April. Skip it if you can have the payer withhold directly (IRA distributions, gambling winnings, pension payments, Social Security) — withholding is simpler and counted as paid evenly through the year. This calculator also does not handle state estimated tax, AMT projections, NIIT, or self-employment-tax computation; use dedicated tools for any of those layered concerns.