Late Tax Payment Penalty & Interest Calculator
Estimate HMRC late payment interest and penalties on an overdue Self Assessment tax bill, for both the standard penalty rules and the newer Making Tax Digital (MTD) for Income Tax penalty regime.
Enter an amount greater than 0.
Enter a rate of 0 or more.
7.75% is HMRC’s published rate from 9 Jan 2026 (Bank of England base rate + 4%). Edit if it has changed.
Payment date must be on or after the due date, and both dates must be valid.
Penalty Timeline
Amount Now Owed — Breakdown
Late Tax Payment Penalty & Interest Calculator (Self Assessment)
If you’ve missed the deadline to pay your Self Assessment tax bill, HMRC charges daily interest on the outstanding amount, and — once you’re far enough overdue — a percentage penalty on top. Which penalty rules apply depends on whether you’re on the standard Self Assessment system or the newer Making Tax Digital (MTD) for Income Tax regime. This calculator estimates both, using HMRC’s current published interest rate.
How Late Payment Interest Works
HMRC charges late payment interest from the day after your payment was due until the day you pay in full. It’s simple daily interest, not compounded: the annual rate is divided by 365 and applied to the outstanding balance for each day it remains unpaid. As of 9 January 2026, HMRC’s published late payment interest rate is 7.75% a year (the Bank of England base rate plus 4 percentage points). This rate is reviewed and can change, so it’s worth checking GOV.UK if your overdue period spans a rate change.
Two Different Penalty Regimes
Most Self Assessment taxpayers are still on the older, more familiar penalty structure. But if you’re self-employed or a landlord with qualifying income over £50,000, you moved onto Making Tax Digital for Income Tax from April 2026, which brings a different, faster-biting penalty timeline. From April 2027 the newer regime is due to extend to all Self Assessment taxpayers.
| Regime | Who it applies to | Payment penalty structure |
|---|---|---|
| Standard Self Assessment | Most individual taxpayers, until 6 April 2027 | 5% of unpaid tax at 30 days, another 5% at 6 calendar months, another 5% at 12 calendar months |
| MTD for Income Tax | Self-employed/landlords with qualifying income over £50,000, in MTD since April 2026, on balancing payments/amounts due (not Payments on Account) | 2026/27 first year: no penalty up to 30 days late; 31+ days late triggers 3% (day 15) + 3% (day 30) + 10% p.a. daily from day 31. From 2027/28: 4% (day 15) + 4% (day 30) + 10% p.a. daily from day 31 |
2026/27 first-year concession: Payments made within 30 days of the due date do not incur the first MTD late-payment penalty. If the payment reaches 31 days late, the day-15 and day-30 penalties become applicable in addition to the day-31 daily charge.
| MTD year | Day 15 | Day 30 | From day 31 |
|---|---|---|---|
| 2026/27 first year | 3% applies if payment reaches 31+ days late | 3% applies if payment reaches 31+ days late | 10% p.a. daily |
| 2027/28 onwards | 4% | 4% | 10% p.a. daily |
Late payment interest applies under both regimes in the same way, calculated separately from the percentage penalties. The MTD late-payment penalty rules covered by this calculator apply to balancing payments/amounts due, not to Payments on Account.
How to Use This Calculator
- Enter the tax owed — the outstanding Self Assessment balance, not including any penalties already charged.
- Check the interest rate — defaults to HMRC’s current published rate; edit it if the rate has since changed or your overdue period spans a rate change.
- Enter the due date — usually 31 January for a balancing payment, or the relevant Payment on Account date.
- Enter the payment date — the date you paid, or expect to pay, in full.
- Select your penalty regime — Standard Self Assessment or MTD for Income Tax. If MTD, also choose the penalty year.
- Click Calculate to see interest, penalties and the total now owed.
Worked Example
Say you owe £3,200 in Self Assessment tax, due 31 January, and you pay it 90 days late. Under the standard regime, that’s past the 30-day mark but short of 6 months, so you’d trigger the first 5% penalty (£160) plus roughly 90 days of interest at 7.75% (around £61), for a total of about £3,421. Under the MTD regime in the 2026/27 first penalty year, 90 days late is past the 31-day point, so both the 3% day-15 penalty and the 3% day-30 penalty apply (£192 combined), plus the 10%-a-year daily charge running from day 31 to day 90 (around £53), plus the same interest. From 2027/28 onwards the same 90-day delay would use 4% at day 15 and 4% at day 30 (£256 combined) instead of 3%/3%, plus the same daily charge and interest — a higher total again. The calculator above works out the exact figures for your numbers and penalty year.
What Counts as “Qualifying Income” for MTD?
Qualifying income is your total gross income from self-employment and property combined, before expenses, based on the tax year two years prior. Sole traders and landlords above £50,000 joined MTD for Income Tax from April 2026; the threshold is due to drop to £30,000 from April 2027 and £20,000 from April 2028, bringing more people into the new regime over time.
Ways to Reduce What You Owe
- Pay what you can now: Penalties are calculated on the outstanding balance, so a partial payment before a threshold date reduces the percentage charged.
- Set up a Time to Pay arrangement: Agreeing a payment plan with HMRC before a penalty date can help you avoid the percentage penalties, though interest still runs on the outstanding balance.
- Check for a reasonable excuse: Circumstances like serious illness, bereavement or an HMRC service failure may waive penalties on appeal — but not the interest itself.
- File and pay early where possible: Interest and the day-count for penalties start from the due date, so earlier payment always reduces the total.
Frequently Asked Questions
Is HMRC late payment interest the same as a penalty?
No. Interest is a separate charge that compensates HMRC for the tax being paid late, and it runs continuously from the day after the due date until you pay, regardless of how many days overdue you are. Penalties are additional percentage charges that only kick in once you pass specific day thresholds (for example, 30 days under the standard regime). Both can apply on the same overdue balance at the same time.
What is HMRC’s current late payment interest rate?
As of 9 January 2026, HMRC’s published late payment interest rate is 7.75% a year, set at the Bank of England base rate plus 4 percentage points. This rate is reviewed periodically and can change if the base rate moves, so always check GOV.UK’s HMRC interest rates page for the current figure if you’re relying on an exact calculation.
Which penalty regime applies to me?
If you’re a sole trader or landlord with qualifying income over £50,000, you should be in Making Tax Digital for Income Tax from April 2026 and subject to its penalty rules. Most other Self Assessment taxpayers remain on the standard penalty structure until at least 6 April 2027, when the newer regime is due to extend to everyone filing a personal Self Assessment return.
Can I appeal a late payment penalty?
Yes. If you have a reasonable excuse — such as a serious illness, bereavement, or an HMRC service failure — you can appeal a penalty. Reasonable excuse claims generally do not remove the interest charged on the unpaid tax, since interest reflects the cost of the money being outstanding rather than a punitive charge.
Does this calculator cover VAT or PAYE penalties?
No. This calculator covers Self Assessment income tax only. VAT operates its own separate points-based penalty and interest system, and PAYE has its own late payment penalty structure. Both differ from the Self Assessment rules covered here.
Does the penalty apply to the whole tax bill or just the unpaid part?
Penalties are calculated on the amount still outstanding at each threshold date, not your original full tax bill. If you’ve made a partial payment before a threshold is reached, the percentage penalty at that stage is calculated on the smaller remaining balance.