The U.S. tax system is pay-as-you-go. If your income is not subject to withholding -- or not enough is withheld -- the IRS expects you to send estimated payments throughout the year. Failing to do so results in penalties that add up faster than most people expect.
Who Must Make Estimated Tax Payments
The IRS requires estimated payments from anyone who expects to owe at least $1,000 in federal tax after subtracting withholding and refundable credits. This commonly includes self-employed individuals and freelancers, small business owners, landlords with rental income, investors with significant capital gains or dividends, and retirees whose pension or Social Security withholding does not cover their full liability.
If you are a W-2 employee whose only income is wages with proper withholding, you probably do not need to make estimated payments. However, if you have a side business, rental properties, or substantial investment income alongside your salary, the withholding from your day job may not be enough. In that case, you either increase your W-2 withholding by updating your W-4 or make quarterly estimated payments to cover the gap.
Quarterly Due Dates
Despite being called quarterly, the four payment periods are not evenly spaced. For the 2025 tax year, the due dates are: Q1 (January 1 through March 31) -- due April 15, 2025; Q2 (April 1 through May 31) -- due June 16, 2025; Q3 (June 1 through August 31) -- due September 15, 2025; and Q4 (September 1 through December 31) -- due January 15, 2026. If any date falls on a weekend or federal holiday, the deadline shifts to the next business day.
You can make payments through IRS Direct Pay, the Electronic Federal Tax Payment System (EFTPS), credit or debit card processors, or by mailing a check with a 1040-ES voucher. IRS Direct Pay and EFTPS are free and provide instant confirmation. Credit card payments incur processing fees of roughly 1.8% to 2%, which is rarely worth it unless you are earning rewards that offset the cost.
Safe Harbor Rules: How to Avoid Penalties
The IRS will not penalize you for underpayment if you meet one of two safe harbor thresholds. The first option: pay at least 90% of your current-year tax liability through estimated payments and withholding. The second option: pay at least 100% of your prior-year tax liability. If your adjusted gross income exceeded $150,000 in the prior year ($75,000 if married filing separately), the prior-year safe harbor rises to 110%.
The prior-year safe harbor is especially useful when your income is unpredictable. If you earned $80,000 last year and paid $14,000 in total tax, you can simply pay $14,000 in estimated taxes this year (or $15,400 if your AGI was above $150,000) and avoid any underpayment penalty -- even if your actual liability turns out to be much higher. You will still owe the balance at filing time, but without the penalty surcharge.
How to Calculate Your Estimated Payments
Start with your expected adjusted gross income for the year. Subtract the standard deduction (or itemized deductions if you itemize), then apply the current tax brackets to calculate your income tax. Add self-employment tax if applicable (15.3% on net self-employment earnings up to the Social Security wage base, then 2.9% on earnings above it). Subtract any credits you expect to claim and any W-2 withholding. The remaining amount is what you need to cover through estimated payments.
The IRS provides a worksheet in Form 1040-ES to walk through this calculation. Many taxpayers simplify by using the prior-year safe harbor: take last year's total tax from line 24 of your Form 1040, divide by four, and pay that amount each quarter. This approach is straightforward and guarantees penalty avoidance, even if your income changes significantly.
Underpayment Penalties and How They Work
If you do not meet either safe harbor threshold, the IRS calculates the underpayment penalty using Form 2210. The penalty rate is the federal short-term rate plus 3 percentage points, compounded daily. For 2025, that rate has been running around 7% to 8% annualized. The penalty is calculated separately for each quarter, so a late Q1 payment accrues more penalty than a late Q4 payment.
There are exceptions. If your total tax liability after withholding is less than $1,000, no penalty applies. The IRS may also waive the penalty if the underpayment was due to a casualty, disaster, or other unusual circumstance, or if you retired or became disabled during the tax year. Additionally, the annualized income installment method (Form 2210, Schedule AI) can reduce or eliminate the penalty if your income was concentrated in certain quarters rather than spread evenly.