Quarterly Estimated Taxes: The Complete 2026 Guide

Who must pay estimated taxes

You generally must make quarterly estimated tax payments if you expect to owe $1,000 or more in federal tax for the year after subtracting your withholding and refundable credits, and your withholding will not reach a safe harbor (90% of this year's tax, or 100% to 110% of last year's). The rules live in IRC section 6654 and the IRS estimated-tax pages, and payments are made with Form 1040-ES or, better, online.

In practice, that describes almost everyone whose income is not fully covered by paycheck withholding:

• Freelancers, consultants, and gig workers paid on 1099s
• Owners of pass-through businesses (sole proprietorships, single-member LLCs, partnerships, S corporations)
• Landlords with rental profit and investors with significant interest, dividends, or capital gains
• Retirees whose pension or IRA withholding falls short
• W-2 employees with a profitable side business the day job's withholding does not cover

Two useful exceptions: there is no penalty for a year if your prior-year tax liability was zero (a full 12-month year in which you were a U.S. citizen or resident), and no payment is required for a quarter if your total expected shortfall stays under the $1,000 threshold. Corporations follow a separate regime with a lower $500 trigger; this guide covers individuals.

The safe harbor rules (IRC 6654)

The IRS does not expect you to predict the year perfectly. You avoid the underpayment addition entirely if your withholding plus timely estimated payments reach the smaller of two targets:

Most people with a filed prior-year return choose the prior-year harbor because it is a known number: divide it by four, pay on schedule, and the penalty math is settled even if the year turns out far better than expected. You settle any remaining balance, without penalty, when you file in April. If you expect income to fall, run both tests and pay the smaller one.

2026 due dates

The four installments are not true calendar quarters. The periods are lopsided (the second covers only two months), which surprises many first-year filers:

A payment made on January 20 for the Q3 installment is still late for Q3, even though the year is not over. Each installment is tested on its own date.

How to pay: Direct Pay, EFTPS, and more

Skip the paper vouchers. Electronic payment gives you an instant confirmation number and a payment history you can pull up years later:

• IRS Direct Pay (irs.gov/payments): free bank-account transfer, no enrollment required. Choose "Estimated Tax" and "1040-ES" for the correct year. Best for most individuals.
• EFTPS (eftps.gov): the Treasury's payment system. Requires enrollment (a PIN arrives by mail), but you can schedule all four installments a year in advance, which is the single best defense against forgetting one.
• IRS Online Account: pay and see your full payment history in one place, useful at filing time when you cannot remember what you paid in June.
• Card or digital wallet: accepted through IRS-approved processors, but they charge a processing fee. Mailing a check with a 1040-ES voucher still works; the postmark date counts as the payment date.

Whichever method you use, record the date, amount, and confirmation number for each payment. Your tax preparer will ask for exactly this list.

Uneven income: the annualized method

Four equal installments assume income arrives evenly. For many freelancers, e-commerce sellers, and anyone with a large year-end payout, it does not. The annualized income installment method (Form 2210, Schedule AI) recomputes each installment based on the income you had actually earned through that period: January-March for Q1, January-May for Q2, January-August for Q3, and the full year for Q4.

If 70% of your income landed in the fourth quarter, the method shrinks the required early installments to match reality and can eliminate the penalty that the equal-installment math would have produced. The cost is bookkeeping: you need income and deduction totals as of each period's cutoff, and Schedule AI is genuinely tedious to complete by hand.

A practical middle path many of our clients use: pay the prior-year safe harbor in four equal pieces when cash flow allows, and reserve the annualized method for years when a big late-year spike would otherwise make the early installments unaffordable.

California is different (Form 540-ES)

States run their own estimated-tax systems, and California's is the one that most often catches people off guard. Instead of four equal installments, the FTB front-loads the year on Form 540-ES:

By June 15, California expects 70% of the year's requirement, and nothing is due with the September federal installment. California's payment threshold is also lower ($500 of expected state tax), its high earners face a mandatory current-year computation (the prior-year harbor is unavailable above certain AGI levels), and most balances must be paid electronically once you cross the FTB's e-pay thresholds. If you owe both federal and California estimates, calendar them as two separate obligations.

What the underpayment penalty really is

"Penalty" is a misleading word here. The IRC 6654 addition works like interest, not a fine: for each installment you underpaid, the IRS charges the federal short-term rate plus 3 percentage points (set quarterly under IRC 6621) on the shortfall, from the installment's due date until the earlier of the date you pay it or the return's April due date. The computation happens on Form 2210, though in most cases the IRS will simply bill the amount if you leave the form off.

The IRS can also waive the addition in limited situations: casualty, disaster, or other unusual circumstances, and certain cases involving retirement or disability. Waivers are requested on Form 2210 with an explanation.

The W-2 withholding fix

Here is the most useful quirk in the entire regime: withholding is treated as paid evenly through the year, no matter when it actually happens (IRC 6654(g)). Estimated payments are credited only on the date paid; withholding is deemed spread across all four installments.

That makes December withholding a legitimate rescue tool. If you discover in November that your installments fell short, you can:

• File a new Form W-4 with your employer to withhold heavily from the remaining paychecks or a year-end bonus
• Request voluntary withholding on an IRA or retirement distribution taken before year-end
• Have a spouse's employer increase withholding when you file jointly

Because that late-year withholding is deemed paid one quarter at a time from April onward, it can retroactively cure earlier underpayments in a way a January estimated payment cannot. It is the standard year-end fix we run for clients with both a W-2 and business income.

Frequently asked questions