Is it better to pay a fourth-quarter estimate or to withhold more in December?

Withholding is treated as paid in four equal parts on the due dates, whatever day it was actually withheld, so tax withheld from a December IRA withdrawal also covers earlier quarters you underpaid; a January estimate only covers the fourth. In the example the same $5,000 leaves a penalty of $86 as an estimate and $0 as December withholding (IRC §6654(g)).

What is the penalty if I pay nothing more for 2026?

Interest at the IRS underpayment rate on each quarter’s shortfall, from its due date until paid or April 15, 2027. In the example that is $172. Already missed a payment? The underpayment penalty calculator works it out to the day.

When are the 2026 estimated tax payments due?

April 15, June 15 and September 15, 2026, and January 15, 2027. No penalty applies when your tax minus withholding is under $1,000, or when you owed no tax for a full 12-month 2025 (Form 2210 instructions).

2026 Estimated Tax Calculator: What to Pay by January 15

The last 2026 estimated tax payment is due January 15, 2027. Enter your 2026 income and what you have paid so far: the tax engine works out your 2026 tax, the safe harbor that keeps the underpayment penalty away, how much is still due, and what the penalty would be if you pay it as an estimate, withhold it in December instead, or pay nothing more.

Already missed a payment? The underpayment penalty calculator prices the penalty to the day. The payment calendar is in the 2026 estimated tax payment schedule.

How much estimated tax should I pay by January 15, 2027?

Pay enough that your 2026 withholding and estimates together reach the safe harbor: the smaller of 90% of your 2026 tax and 100% of your 2025 tax (110% if your 2025 AGI was over $150,000), IRC §6654(d). Whatever is still short is your January 15 payment. Example: a single 67-year-old with a $30,000 pension, $60,000 of IRA withdrawals, $30,000 of Social Security, $5,000 of interest and a $20,000 long-term gain owes $19,774 for 2026; with a 2025 tax of $14,000 the safe harbor is $14,000. Having had $3,000 withheld and paid three $2,000 estimates, they still need $5,000 by January 15, 2027. Paid as the fourth estimate, that leaves a penalty of $86 for the quarters already short; the same amount withheld from a December IRA withdrawal instead leaves $0, because withholding counts as paid evenly through the year. Paying nothing more costs $172.

The worked example, computed by the tax engine (single, 67; 2025 tax $14,000, 2025 AGI $100,000; $3,000 withheld; $2,000 paid on each of the first three due dates).
Key number	2026
2026 tax (the Form 2210 figure) (Form 2210)	$19,774
Safe harbor: required annual payment (§6654(d))	$14,000
Required per quarter	$3,500
Still to pay by January 15, 2027	$5,000
Penalty if paid as the January 15 estimate (IRS rates)	$86
Penalty if withheld in December instead (§6654(g))	$0
Penalty if nothing more is paid	$172

An estimate from QuantCalc’s open tax engine (federal 2.0.0, state 1.12.0) for the 2026 tax year. Not tax advice: your return depends on facts this page does not ask about, so check a move with your tax preparer or custodian before acting. Penalty interest after January 1, 2027 uses the last announced IRS rate (7%, Rev. Rul. 2026-15, as published on IRS quarterly interest rates) carried forward, because the IRS has not announced that quarter yet. How the engine computes each line, with its official source: federal, state.

Calculate your January 15 payment

Your household

Filing status Your age on Dec 31, 2026

2026 income (the whole year, expected)

Wages ($) Pension or annuity ($) IRA / 401(k) withdrawals ($)Including RMDs and conversions Social Security ($)Gross benefits Taxable interest ($) Qualified dividends ($) Net long-term capital gains ($)

Paid so far, and last year

Federal tax withheld in 2026 ($)Whole year, including what is still to come Estimate paid by April 15 ($) Estimate paid by June 15 ($) Estimate paid by September 15 ($) Your 2025 total tax ($)Form 1040 line 24 for 2025 2025 AGI over $150,000 ($75,000 married filing separately)?

Estimates count as paid on their due date. A payment made late, or a missed one, is priced to the day by the underpayment penalty calculator.

Example — enter your numbers

The 2026 due dates

The four installments of 2026 estimated tax are due on these dates:

Installment 1: April 15, 2026
Installment 2: June 15, 2026
Installment 3: September 15, 2026
Installment 4: January 15, 2027

Each installment is a quarter of the required annual payment. A shortfall in one quarter accrues interest at the IRS underpayment rate until it is paid or until April 15, 2027, whichever comes first.

Why December withholding can beat a January estimate

Tax withheld during the year is treated as paid in four equal parts on the four due dates, unless you elect otherwise, whatever day it was actually withheld (IRC §6654(g)). An estimated payment counts only from the day you make it. So if the first three quarters are short, asking your IRA custodian to withhold the shortfall from a December distribution covers those quarters retroactively, while a January 15 estimate covers only the fourth. The calculator shows both.

Common questions

How much estimated tax should I pay by January 15, 2027?: Enough that your 2026 withholding and estimates reach the safe harbor: the smaller of 90% of your 2026 tax and 100% of your 2025 tax (110% if your 2025 AGI was over $150,000). In the worked example that is $14,000, of which $5,000 is still due by January 15, 2027.
Is it better to pay a fourth-quarter estimate or to withhold more in December?: Withholding is treated as paid in four equal parts on the due dates, whatever day it was actually withheld, so tax withheld from a December IRA withdrawal also covers earlier quarters you underpaid; a January estimate only covers the fourth. In the example the same $5,000 leaves a penalty of $86 as an estimate and $0 as December withholding (IRC §6654(g)).
What is the penalty if I pay nothing more for 2026?: Interest at the IRS underpayment rate on each quarter’s shortfall, from its due date until paid or April 15, 2027. In the example that is $172. Already missed a payment? The underpayment penalty calculator works it out to the day.
When are the 2026 estimated tax payments due?: April 15, June 15 and September 15, 2026, and January 15, 2027. No penalty applies when your tax minus withholding is under $1,000, or when you owed no tax for a full 12-month 2025 (Form 2210 instructions).