Can a Year-End Payment Erase an Underpayment Penalty? (w/Examples) + FAQs

Quick Answer

No — for tax year 2025, a year-end estimated tax payment usually cannot fully erase an underpayment penalty, because the IRS charges the penalty quarter by quarter under Internal Revenue Code section 6654. A late lump sum only stops the clock going forward. But a year-end withholding boost often can erase it.

Introduction

You opened a notice, or your tax software flashed a penalty, and you owe the IRS extra money for not paying enough during the year. The natural reaction is to write one big check in December and hope it cleans up the whole mess. It rarely does, because the estimated tax system treats the year as four separate deadlines, and a payment made in December does nothing for a deadline you missed back in April.

This matters because the penalty is really interest, and it keeps growing until you pay. The penalty rate sat at 7% for all of 2025 and the first quarter of 2026, then dropped to 6% for the second quarter of 2026. The IRS reports that millions of taxpayers pay this penalty each year, and most could have avoided it with one timing move. The trick is knowing the one type of payment the law treats as if you made it evenly all year.

This article reflects federal rules as of June 2026 and covers tax year 2025. It mentions a few common state rules but is not a state-by-state guide. Tax law changes, so confirm current figures before you file. This is educational information, not advice for your specific situation. For a complex year — large capital gains, a business sale, or a notice you do not understand — talk to a CPA or tax attorney.

Here is what you will learn:

🧾 Why the IRS splits the year into four “installments” and charges each one separately.
💡 The withholding loophole that can erase a penalty even in late December.
🧮 Three fully worked examples with real dollar math you can copy.
📅 The deadlines, forms, and the one date that lets a Q4 payment count.
⚠️ Seven mistakes that quietly cost people hundreds of dollars.

What the Underpayment Penalty Really Is

The underpayment penalty is not a flat fine. It is interest the IRS charges on money you should have paid earlier in the year but did not. The rule lives in section 6654 of the tax code, which says taxes are “pay-as-you-go.” You are expected to pay tax as you earn income, not in one chunk at filing time.

The IRS sets the rate every quarter at the federal short-term rate plus three points, and it compounds daily. For 2025 and the first quarter of 2026 that rate was 7% per year. For the second quarter of 2026 it fell to 6%. Because the rate is tied to interest, the longer a shortfall sits unpaid, the bigger the penalty grows.

The most important detail is timing. The IRS does not look at whether you paid enough by April 15 of the next year. It looks at whether you paid enough by each of the four deadlines during the year. Miss an early deadline, and the penalty starts running from that date — even if you overpay later. This is the single fact that makes a “fix it in December” plan fail.

A common misconception is that you are safe if you get a refund. You can still owe this penalty even when you are due a refund, because the penalty is about when you paid, not whether you ended up overpaying. The fix is to understand the four installments before you decide how to catch up.

The Four Installments: Why One Late Payment Doesn’t Fix It

The IRS divides the tax year into four payment periods, each with its own due date. For income earned in tax year 2025, the estimated tax deadlines are April 15, 2025, June 16, 2025, September 15, 2025, and January 15, 2026.

Each deadline is its own little finish line. If your required payment for the first period was $2,500 and you paid nothing, the penalty starts running on that $2,500 from April 15, 2025. Paying $10,000 in December 2025 does not travel back in time to cover April. The IRS applies your December payment to the current period first, so the early shortfall keeps accruing interest right up until you actually pay it.

The consequence is real money. Suppose you owed $2,500 each quarter and paid the full $10,000 in one December check. The IRS still charges roughly 7% interest on the April shortfall for about eight months, on the June shortfall for about six months, and on the September shortfall for about three months. That can total well over $300, even though you “paid everything” before year-end.

The misconception here is that the total dollars are what count. They are not — the date of each payment is what counts. The next step is to learn the one payment type that escapes this trap.

The Withholding Trick: The One Payment That Looks Like You Paid All Year

Here is the rule that changes everything. Money withheld from your pay, pension, Social Security, or an IRA distribution is treated by section 6654 as if you paid it evenly across all four quarters — no matter when in the year it was actually withheld.

That means a withholding boost in late December counts as though one-fourth of it was paid back in April, one-fourth in June, and so on. So if you are a W-2 employee, or you take a year-end bonus, or you take a required minimum distribution (RMD) from a retirement account, you can ask the payer to withhold a large amount in December — and the IRS spreads it backward over the whole year. This can erase penalties from earlier quarters.

A year-end estimated tax payment (Form 1040-ES) does not get this treatment. It is credited only on the date you make it. This is the core difference, and it is why two people who pay the exact same amount on the exact same December day can get completely different penalties.

The misconception is that “a payment is a payment.” It is not. Withholding is deemed even; estimated payments are dated. What you should do: if you have any wage, pension, or retirement income left before year-end, route your catch-up through withholding, not an estimated payment.

How to Trigger Year-End Withholding

You have three common levers. First, a W-2 employee can file a new Form W-4 and add an extra flat amount on Step 4(c) for the last paychecks of the year. Second, if you take an IRA or 401(k) distribution, you can ask the custodian to withhold a large percentage — even up to 100% of the distribution in some cases.

Third, a working spouse can crank up their withholding to cover both spouses on a joint return, since withholding is pooled. The consequence of using this lever is powerful: a $6,000 December withholding is treated as $1,500 paid each quarter, which can wipe out earlier-quarter penalties. The deadline is hard — the money must be withheld by December 31, 2025 for the 2025 tax year. After that, only an estimated payment is possible, and it will not spread backward.

Worked Example #1: The December Estimated Payment That Fails

Meet Maria, a freelance graphic designer. She owes $12,000 in tax for 2025 and made no estimated payments and had no withholding. Her required annual payment under the 90% safe harbor is about $10,800, or roughly $2,700 per quarter.

In late December 2025, Maria sends one $10,800 estimated payment to catch up. Because it is an estimated payment, the IRS credits it only on the December date. The April installment was short by $2,700 for about 8 months, the June installment for about 6 months, and the September installment for about 3 months.

Here is the math at the 7% rate. The April shortfall: $2,700 × 7% × (250 days ÷ 365) ≈ $129. The June shortfall: $2,700 × 7% × (188 days ÷ 365) ≈ $97. The September shortfall: $2,700 × 7% × (97 days ÷ 365) ≈ $50. The Q4 installment was paid on time, so it adds nothing. Maria’s penalty is roughly $276, even though she “paid in full” before New Year’s Eve.

Worked Example #2: The Withholding Move That Erases It

Now meet David, a software engineer with the exact same problem: $12,000 owed, nothing paid in during the year. The difference is that David is a W-2 employee.

In December 2025, David files a new Form W-4 and asks his employer to withhold an extra $10,800 from his last two paychecks. Because withholding is deemed paid evenly, the IRS treats this as $2,700 paid in April, June, September, and January — exactly matching each required installment.

The result: David has no shortfall in any quarter. His underpayment penalty is $0. Same income, same total payment, same December timing as Maria — but because David used withholding instead of an estimated check, his penalty disappears entirely.

Worked Example #3: The Annualized Method for Lumpy Income

Meet Priya, a consultant who earned almost nothing for the first three quarters and then closed a $200,000 project in December 2025. The standard penalty rules assume your income is spread evenly, so they would expect her to have paid big installments back in April — before she had any money.

Priya uses the annualized income installment method on Schedule AI of Form 2210. This method matches each required installment to the income she actually earned in each period. Because she earned little before October, her required payments for the first three quarters were tiny.

When she makes a large estimated payment in January 2026 (the Q4 deadline) covering the income she earned in Q4, the annualized method shows she paid the right amount in each period. Her penalty drops to $0 or close to it — not by paying differently, but by proving her income was lumpy and her early installments were small. She checks Box C in Part II of Form 2210 and attaches Schedule AI.

Which Situation Applies to You?

The right fix depends on your income type and how much time is left in the year. Use this to find your path.

You have W-2 wages, a pension, or Social Security: Increase withholding before December 31. This is the only way to retroactively cover earlier quarters. Go to the withholding section above.
You can take a retirement distribution (RMD or otherwise): Have the custodian withhold a large amount. Same even-spreading benefit as wage withholding.
You are fully self-employed with no wages: You cannot use the withholding trick. Pay your Q4 estimated payment by January 15, 2026, and consider the annualized method if your income was uneven.
Your income spiked late in the year: Use Schedule AI (annualized method) on Form 2210 to match installments to when you earned the money.
You missed only the last quarter: A January 15, 2026 estimated payment fully fixes Q4, since you are still on time for that installment.

Safe Harbors: The Real Way to Be Penalty-Proof

The cleanest way to avoid the penalty is to land inside a “safe harbor.” If you meet one, you owe no penalty regardless of how big your final bill is. The IRS safe harbor rules give you three off-ramps.

First, you owe no penalty if your total tax due after withholding is less than $1,000 for the year. Second, you are safe if you paid at least 90% of the current year’s tax. Third, you are safe if you paid at least 100% of last year’s tax — or 110% if your prior-year AGI was over $150,000 ($75,000 if married filing separately).

The prior-year safe harbor is the most reliable, because last year’s number is already fixed and known. The consequence of using it: you can owe a giant balance in April and still face no penalty, as long as your withholding plus estimates hit that prior-year target on time.

The misconception is that the safe harbor protects you from the tax bill. It does not — it only protects you from the penalty. You will still owe every dollar of tax at filing. What to do: pick the prior-year number, divide by four, and pay that much each quarter (or withhold it).

Special Rule for Farmers and Fishers

If at least two-thirds of your gross income comes from farming or fishing, you get a softer rule. Your required annual payment is only 66.67% of the current year’s tax (instead of 90%), and you can avoid estimated payments entirely by filing and paying your full bill by March 1.

If you skip the March 1 option, make a single estimated payment by January 15 to stay penalty-free. The consequence of missing both dates is a penalty figured on Form 2210-F. For tax year 2025, Notice 2026-3 added limited penalty relief tied to certain qualified farmland sales — a narrow rule worth asking a CPA about if it could apply to you.

Federal vs. State: Do Not Assume They Match

The withholding trick and the safe harbors above are federal rules. Most states copy the basic pay-as-you-go idea, but the numbers and the rescue methods differ, so never assume your state follows the federal playbook.

State Approach	What to Know
California (FTB)	Requires estimated payments on an uneven schedule — 30% for Q1, 40% for Q2, 0% for Q3, and 30% for Q4 — and high earners must use 90% of current-year tax, per the Franchise Tax Board.
No-income-tax states	States like Texas, Florida, and Washington have no individual income tax, so there is no state estimated tax penalty to worry about at all.
Most other states	Generally mirror the federal $1,000 threshold and prior-year safe harbor, but penalty rates and forms are set by the state revenue agency, not the IRS.

The consequence of guessing wrong is a separate state penalty notice months later. What to do: check your state revenue department’s estimated tax page for its own deadlines, percentages, and safe harbor before you rely on the federal rules.

Form 2210: How to Calculate and Claim Your Fix

Form 2210 is where you figure the penalty yourself or ask the IRS to reduce it. Most people do not need to file it — the IRS will calculate the penalty and send a bill. You file it only when you want to lower the penalty using a special method.

Part I figures your “required annual payment” — the smaller of the 90% current-year or 100%/110% prior-year safe harbor. Part II is the key decision box: you check Box C to use the annualized method (Schedule AI) for uneven income, or Box D to have your withholding counted on the actual dates it was taken rather than spread evenly. Box A requests a full waiver; Box B requests a partial one.

Part III computes the penalty installment by installment. If you check Box C, you must complete Schedule AI, which splits the year into the four periods, annualizes your income in each, and sets a smaller required installment for the low-income periods. The deadline to file Form 2210 is with your tax return — by April 15, 2026 for the 2025 tax year, or by your extended due date.

The Box D Move for Front-Loaded Withholding

Box D is the quiet hero for anyone who had most of their tax withheld late in the year. By default the IRS spreads withholding evenly, which usually helps. But if your withholding was heavy early and light late, checking Box D and using the actual withholding dates can produce a lower penalty.

You only use Box D when it helps you, and the form lets you compare. The consequence of ignoring it is overpaying a penalty you did not owe. The step: run the numbers both ways in your tax software, and choose the method that gives the smaller penalty.

Mistakes to Avoid

Making a December estimated payment instead of withholding. The estimated payment is dated, so it leaves earlier-quarter penalties fully intact.
Assuming a refund means no penalty. You can owe the penalty even with a refund, because it is based on when you paid.
Skipping the annualized method on lumpy income. Not filing Schedule AI can leave hundreds of dollars in penalties on the table for late-year income.
Forgetting the 110% rule for higher earners. If your prior-year AGI topped $150,000, paying only 100% of last year’s tax still triggers a penalty.
Missing the January 15 fourth-quarter deadline. A Q4 payment one day late converts an on-time installment into a penalized one.
Treating the safe harbor as a tax cap. It blocks the penalty only — you still owe the full tax bill at filing.
Assuming your state mirrors federal. California’s uneven 30/40/0/30 schedule alone trips up taxpayers who paid evenly.
Not increasing a spouse’s withholding. On a joint return, withholding is pooled, and many couples miss this easy fix.

Do’s and Don’ts

Do’s

Do route catch-up money through withholding when you can, because it is treated as paid evenly all year.
Do use the prior-year safe harbor as your target, since the number is fixed and known.
Do consider an IRA distribution with heavy withholding late in the year, because the withholding spreads backward.
Do file Schedule AI if your income was uneven, to match installments to real earnings.
Do check your state’s separate rules, because state deadlines and percentages often differ from federal.

Don’ts

Don’t wait until April to fix an underpayment, because the penalty grows daily until you pay.
Don’t rely on a December estimated check to undo earlier-quarter shortfalls, because it only counts from its date.
Don’t ignore an IRS penalty notice, because interest keeps compounding while you delay.
Don’t assume reasonable cause works — the estimated tax penalty generally cannot be waived for reasonable cause, only for disasters or specific events.
Don’t forget married-filing-separately limits, since the 110% trigger drops to $75,000 of AGI for that status.

Pros and Cons of Using a Year-End Withholding Boost

Pros

It can erase earlier-quarter penalties entirely, because withholding is deemed paid evenly.
It needs no special form beyond a new W-4 or a custodian request, so it is simple to execute.
It works even on December 31, giving you a last-minute rescue an estimated payment cannot provide.
It can cover a spouse, since joint-return withholding is pooled.
It avoids interest pile-up, because it treats the money as on time from April forward.

Cons

It only works if you have wage, pension, or retirement income to withhold from.
A large withholding cuts your take-home pay sharply in the final paychecks.
A heavy IRA withholding reduces the cash that actually reaches your account.
It requires acting before December 31, leaving no room for delay.
It will not reduce your actual tax, only the penalty and the timing problem.

What to Do Next

Run a safe harbor check now. Pull last year’s total tax, multiply by 100% (or 110% if your AGI was over $150,000), and confirm whether your payments so far hit that target on time.
If you are short, choose withholding over an estimated payment whenever you have wages, a pension, or a retirement distribution available before December 31.
If your income was uneven, plan to file Form 2210 with Schedule AI and check Box C to use the annualized method.
Gather your records — pay stubs, 1099s, payment confirmations, and last year’s return — so you can complete the form accurately.
Mark January 15, 2026 as your final 2025-tax-year estimated payment deadline if you are self-employed.
Call a CPA or enrolled agent if you had a large capital gain, sold a business, or received an IRS notice you do not understand.

FAQs

Can I erase an underpayment penalty with a year-end estimated payment?

No. For tax year 2025, an estimated payment counts only on the date you make it, so it cannot undo shortfalls from April, June, or September. It only stops the penalty from growing further on those amounts.

Does withholding really count as paid evenly all year?

Yes. Under section 6654, federal income tax withheld is treated as paid in equal amounts across the four installment dates, regardless of when it was actually withheld during the year.

How much is the underpayment penalty rate right now?

It was 7% in 2025 and the first quarter of 2026, then dropped to 6% for the second quarter of 2026, per the Federal Register. The rate is set quarterly and compounds daily.

What are the estimated tax deadlines for 2025 income?

April 15, 2025, June 16, 2025, September 15, 2025, and January 15, 2026. Each is a separate deadline, and missing any one can start a penalty for that period.

Can I avoid the penalty if I’m getting a refund?

No. A refund does not protect you, because the penalty is based on whether you paid enough on time during the year, not on whether you overpaid by the end.

What is the easiest safe harbor to rely on?

Paying 100% of last year’s tax (110% if your prior-year AGI exceeded $150,000) is the most reliable, because the prior-year figure is already fixed and easy to divide into four payments.

How do I take a retirement distribution to fix this?

Ask your IRA or 401(k) custodian to withhold a large percentage of the distribution. That withheld tax is treated as paid evenly all year, which can erase earlier-quarter penalties before December 31.

Do I have to file Form 2210?

No, usually. The IRS calculates the penalty and bills you. You file Form 2210 only to lower the penalty using the annualized method, the actual-withholding-dates method, or to request a waiver.

What is the annualized income installment method?

It matches your required payments to when you actually earned income. You report income period by period on Schedule AI, which shrinks early installments if your income arrived late in the year.

Can the penalty be waived for reasonable cause?

No, generally not. The IRS states the estimated tax penalty cannot be waived for reasonable cause, though it may be reduced for a casualty, disaster, retirement after 62, or disability.

Does my state follow the federal withholding rule?

Often, but not always. Many states mirror the federal approach, but California requires an uneven 30/40/0/30 schedule and high earners must hit 90% of current-year tax, per the Franchise Tax Board.

What if I only missed the fourth quarter?

Pay your Q4 estimated tax by January 15, 2026. Since that installment is not yet late, a payment by the deadline fully covers it and you owe no penalty for that period.

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