Estimated Tax Payments: Safe Harbors, 2026 Deadlines and How to Avoid Penalties

By Tom, CPA · Updated October 27, 2026

Part of: Tax Planning

TL;DR: If you expect to owe $1,000 or more after withholding, you generally need quarterly estimated payments. You avoid the penalty by paying at least 90% of this year's tax or 100% of last year's (110% if last year's AGI was over $150,000). The last 2026 payment is due January 15, 2027.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

The U.S. tax system is pay-as-you-go. Employees pay through withholding; everyone else, including the self-employed, landlords, investors and early retirees, pays through quarterly estimated tax payments. Miss them and you face an underpayment penalty, which works like interest on the shortfall.

The good news: safe harbor rules let you avoid the penalty entirely with a simple calculation based on last year's return. This guide covers who must pay, the safe harbors, due dates, the annualized method for uneven income and how to pay. Rules are from IRS Topic 306 and Publication 505, as of October 27, 2026. Also see the estimated tax calculator, estimated taxes for early retirees and rental property estimated taxes.

CPA Warning Label: Estimated taxes are the IRS's way of reminding you that it would like its money before April, thank you, and that it charges interest if you make it wait.

Who must pay

You generally must make estimated payments for 2026 if both are true:

1. You expect to owe at least $1,000 in federal tax for 2026 after subtracting withholding and refundable credits.
2. Your withholding and refundable credits will be less than the smaller of 90% of your 2026 tax or 100% of your 2025 tax (110% for higher incomes).

Common situations:

• Self-employment and side business income, which also carries 15.3% self-employment tax.
• Rental income.
• Large capital gains, dividends and interest.
• Early retirees doing Roth conversions or selling taxable investments.
• Retirees with pensions or IRA withdrawals without enough withholding.
• Gig workers and freelancers paid on 1099s.

No penalty applies if you had no tax liability for the prior full year and were a U.S. citizen or resident, or if the total owed is under $1,000.

100%/110% safe harbors

You avoid the underpayment penalty if your timely payments (withholding plus estimates) total at least the smaller of:

The prior-year safe harbor is the planner's favorite because it is known in advance. Look at line 24 (total tax) on your 2025 Form 1040, multiply by 100% or 110%, subtract expected withholding, and divide the rest into four payments. Even if 2026 income doubles, there is no penalty; you just owe the balance by April 15, 2027.

Farmers and fishermen have special rules (66⅔% of current-year tax, or one payment by January 15). Special rules also cover casualty, disaster and retirement or disability situations, where the IRS may waive the penalty.

Due dates

The "quarters" are uneven: two months, then three, then four. If a due date falls on a weekend or holiday, it moves to the next business day. You can skip the January payment if you file your 2026 return and pay all tax due by February 1, 2027.

States that have an income tax usually require their own estimated payments, often on the same schedule, with their own safe harbors.

The withholding shortcut

Withholding is treated as paid evenly through the year, no matter when it actually happens. A retiree who has a large amount withheld from a December IRA distribution can cover a shortfall for the entire year, avoiding penalties for earlier quarters. Employees can do the same by increasing withholding late in the year. See withholding vs estimates from an IRA.

Annualized method

If income is uneven, for example a large capital gain in November or a business that earns most of its money in the fall, equal quarterly payments can overpay early. The annualized income installment method (Form 2210, Schedule AI) calculates each installment based on income actually earned through the end of each period.

• A November gain only needs to be covered by the January 15 payment.
• You must attach Schedule AI to your return to claim the lower required installments.
• Tax software handles the computation, but you need records of income by period.

The annualized method is particularly useful for early retirees who do a big Roth conversion in December after seeing the year's income, or for anyone who sells a rental late in the year.

Paying online

• IRS Direct Pay: free bank transfer, no registration; choose "estimated tax" and the year.
• IRS Online Account: pay and see payment history, which is useful at filing time.
• EFTPS: free, requires enrollment; can schedule a year of payments in advance.
• Debit or credit card: through approved processors, for a fee.
• Check with Form 1040-ES voucher: still works; mail early.

Keep confirmation numbers. When you file, report the total of estimated payments made for the year; mismatches with IRS records are a common cause of refund delays.

The penalty

The penalty is computed like interest on each late installment at the federal short-term rate plus 3 percentage points, adjusted quarterly, from the due date until paid or April 15, whichever is earlier. It is not deductible. At recent rates, underpaying $10,000 by six months costs a few hundred dollars: annoying, not catastrophic.

How much to pay each quarter

There are three common approaches, from simplest to most precise.

1. Prior-year safe harbor. Take 100% or 110% of last year's total tax, subtract expected withholding, and pay a quarter of the remainder on each date. Zero penalty risk, though you may owe a large balance in April if income rose.
2. Current-year projection. Estimate this year's tax with the Form 1040-ES worksheet or software and pay 90% in four installments. Better for years when income is falling, such as the first year of early retirement, because it avoids overpaying based on a high-income prior year.
3. Annualized. Recalculate each quarter from actual year-to-date income. Most work, most precise; best for lumpy income.

Many people mix them: use the prior-year safe harbor for the first two payments, then switch to a current-year projection in September once the year's picture is clear. Just remember that the safe harbor test applies to each installment, so underpaying an early quarter and catching up later can still produce a small penalty for the early period unless withholding is used to catch up.

First year of early retirement

The year after you leave a high-paying job is the classic trap. The prior-year safe harbor might be $50,000 or more, based on a working year, while actual tax in a low-income retirement year might be under $5,000. Paying 90% of the current year's projected tax is usually the better choice, but it requires a reasonable estimate. If you are doing a Roth conversion late in the year, the annualized method lets you pay for it in January.

Self-employment tax

Estimated payments must cover self-employment tax, not just income tax. At 15.3% on most net self-employment earnings up to the Social Security wage base ($184,500 in 2026), it is often the larger of the two for small businesses.

Illustration

Jamie left a job in 2025 and now runs a consulting business and owns two rentals. Her 2025 total tax was $28,000 and 2025 AGI was $190,000. She has no withholding in 2026.

• Safe harbor: 110% of $28,000 = $30,800.
• Quarterly payments: $7,700 each on April 15, June 15, September 15 and January 15.
• Her 2026 tax ends up $41,000. She owes $10,200 with her return by April 15, 2027, with no underpayment penalty.
• Had she paid only $5,000 per quarter, she would have covered $20,000, below the $30,800 safe harbor and below 90% of her actual tax, and the penalty would run on each quarter's shortfall from its due date.

If her spouse were still employed, the couple could instead raise the spouse's W-4 withholding for the rest of the year to cover the safe harbor, since withholding counts as paid evenly. See the W-4 withholding guide.