Use this underpayment penalty calculator to see what a late or missed estimated tax payment will cost you. The IRS penalty works like interest. For 2026, it runs at 6% to 7% a year on the amount you underpaid, for each day it was late. Missing a $3,000 payment in June and paying it with your return in April costs about $174.
That’s annoying, but rarely a disaster. Even so, it’s easy to avoid with the right plan for quarterly estimated taxes.
How to use the underpayment penalty calculator
- Enter the amount you underpaid for one quarter.
- Pick the payment that was late or missed.
- Enter the date you paid it. If you haven’t paid yet, leave April 15, 2027, which is when the penalty stops counting.
- Press “Calculate penalty.” For more than one late quarter, run it once for each and add the results.
Underpayment penalty calculator (2026 tax year)
Estimate the IRS penalty for one late or missed estimated tax payment.
Uses the IRS underpayment rates for 2026 (7% Jan–Mar, 6% Apr–Jun, 7% Jul–Dec) and assumes 7% for 2027 until the IRS announces it. The penalty stops on April 15, 2027. This is an estimate, not the IRS’s official Form 2210 calculation.
How the underpayment penalty works
The IRS charges the penalty when you pay too little estimated tax by any of the four due dates. It’s based on three things:
- How much you underpaid for that quarter.
- How many days it was late, from the day after the due date until you paid.
- The IRS underpayment interest rate, which the IRS sets every quarter. It equals the federal short-term rate plus 3 percentage points.
Each quarter is judged on its own. So paying extra in September doesn’t fix a June shortfall for the months it was late. That’s why the estimated tax due dates matter as much as the total you pay.
Current IRS underpayment rates
| Period | Annual rate |
|---|---|
| January to March 2026 | 7% |
| April to June 2026 | 6% |
| July to September 2026 | 7% |
| October to December 2026 | 7% |
| January to March 2027 | Not announced yet (the calculator assumes 7%) |
The rate isn’t compounded for this penalty. However, if you then leave a balance unpaid after April 15, separate interest and late-payment penalties can start.
Examples from the underpayment penalty calculator
Each example below uses a $3,000 shortfall for the 2026 tax year.
| Situation | Days late | Penalty |
|---|---|---|
| April payment missed, paid April 15, 2027 | 365 | $203.75 |
| June payment missed, paid April 15, 2027 | 304 | $173.67 |
| June payment paid one month late | 30 | $16.03 |
| September payment missed, paid April 15, 2027 | 212 | $121.97 |
| January payment missed, paid April 15, 2027 | 90 | $51.78 |
The earlier the missed quarter, the more it costs, because the penalty has more days to build up. Also, notice how small the penalty is when you catch up quickly.
What missing every quarter costs
Now suppose a freelancer skips all four payments for 2026, $12,000 in total, and pays everything with the return on April 15, 2027. The calculator puts the penalty at about $551.
That’s roughly 4.6% of the tax owed. On top of that, paying $12,000 at once in April can be a real shock to your cash flow, which is often the bigger problem.
How to avoid the underpayment penalty
- Owe less than $1,000. If the balance on your return is under $1,000, there’s no penalty at all.
- Use the safe harbor rule. Pay at least 90% of this year’s tax, or 100% of last year’s. If last year’s adjusted gross income was over $150,000, use 110%.
- Check the first-year exception. If you had no tax liability last year and were a U.S. citizen or resident all year, you owe no penalty this year.
- Use the annualized income method. If most of your income came late in the year, Form 2210 lets you match each payment to when you actually earned the money. This can cut the penalty or remove it.
- Ask for a waiver if you qualify. The IRS can waive it after a casualty, a disaster or other unusual event, or if you retired after 62 or became disabled.
- Catch up as soon as you can. Every day you wait adds to the penalty, so pay the missing amount right away.
How a late payment is applied
The IRS applies each estimated payment to the earliest quarter that’s still short. That rule works in your favor. As soon as you pay, the penalty on the oldest shortfall stops growing.
For example, say you owed $3,000 on June 15 but paid only $1,500. Then, on September 15, you paid $4,500. The first $1,500 of that payment covers June, and the rest counts toward September.
| Situation | Days late | Penalty |
|---|---|---|
| Half of the June payment ($1,500) paid on September 15 | 92 | About $26 |
| All of the June payment ($3,000) paid on September 15 | 92 | About $52 |
| All of the June payment left until April 15, 2027 | 304 | About $174 |
In short, a partial payment on time is always better than nothing. Likewise, a late payment is far better than waiting for your return.
The W-2 withholding trick
If you also have a job, you have a useful tool. By default, the IRS treats tax withheld from your paycheck as paid evenly through the year. That’s true even if most of it was withheld in December.
So, if you missed estimated payments earlier in the year, raise your withholding on a new Form W-4 for your last few paychecks. The extra tax then counts toward every quarter, and it can wipe out the penalty for earlier ones. A spouse’s withholding works too if you file jointly.
The underpayment penalty vs other IRS charges
People often mix up these charges. Each one has a different trigger and cost.
| Charge | When it applies | How much |
|---|---|---|
| Underpayment penalty | Estimated tax paid late or too little during the year | Interest-like rate, 6% to 7% a year in 2026 |
| Failure-to-pay penalty | Tax still unpaid after the April deadline | 0.5% of the unpaid tax per month, up to 25% |
| Failure-to-file penalty | Return filed late without an extension | 5% of the unpaid tax per month, up to 25% |
| Interest | Any balance unpaid after the deadline | The same quarterly IRS rate, compounded daily |
The failure-to-file penalty is by far the most expensive. Therefore, always file on time, or file for an extension, even if you can’t pay the full balance yet.
If you get a penalty notice
If you didn’t figure the penalty on your return, the IRS may send notice CP30 later. Don’t ignore it. First, check that the IRS has every payment you made. Then decide whether the annualized method, a safe harbor or a waiver applies. If none does, pay the amount by the date on the notice to avoid more interest.
A simple system so it doesn’t happen again
- Move a fixed share of every client payment into a tax savings account. Our guide on how much to set aside for taxes shows the right percentage.
- Keep that money apart from your spending. A separate bank account for freelancers makes this almost automatic.
- Schedule all four payments in January and adjust them each quarter.
Frequently asked questions
Is this underpayment penalty calculator exact?
It’s a close estimate. It uses the IRS’s published rates and counts each day late, like Form 2210 does. The official figure can differ slightly if you made several partial payments or use the annualized income method.
Do I have to file Form 2210 myself?
Usually not. The IRS can figure the penalty and send you a bill. You only need Form 2210 if you want to use the annualized method, ask for a waiver or show that a safe harbor applies.
Is the underpayment penalty tax-deductible?
No. IRS penalties can’t be deducted as a business expense or on your personal return.
What’s the fastest way to catch up on a missed payment?
Pay online the same day. Our step-by-step guide shows how to pay estimated taxes online for free with IRS Direct Pay.
This article is for general information only and is not legal, tax or financial advice. The calculator gives an estimate, not the IRS’s official calculation.