Late Tax Return Penalty Calculator 2026
Quickly estimate how much you'll pay in penalties and interest for a late return
Using the calculator to estimate late filing penalties for Self Assessment
Our free calculator will help you estimate how much you can expect to pay in penalties and interest on top of the tax you owe if you are late submitting your Self Assessment tax return, or paying the bill.
HMRC issue an automatic £100 penalty if you’re just one day late submitting, and this increases the longer you delay. You can also be fined for missing the deadline to register for Self Assessment! Read our article for more information about what happens if your Self Assessment is late.
How much do I pay if my tax return is late?
It really depends on how late you are! If you’re between one day and three months overdue submitting your return, you’ll receive an automatic £100 penalty. After that, a £10 daily fine applies until you hit the six-month mark.
Hopefully, you’ve settled things by then – because after six months, it gets more serious. You’ll face either a £300 flat fine or 5% of your total tax bill (whichever is higher), on top of any previous charges. You’ll also receive separate penalties if you haven’t yet paid the bill.
In short: the longer you wait, the more it costs!
FAQs
If you want to get it to HMRC as quickly as possible, same or next day payments can be sent by Faster Payments (online or by telephone banking), through your online bank account, by debit or credit card online, CHAPS, or at your bank or building society.
You can also set up a direct debit, but just be aware this will take up to five working days if you don’t already have one set up with HMRC.
Yes, if you’re expecetd to file a Self Assessment but don’t, you’ll still face the same late filing penalties for missing the Self Assessment deadline, even if you don’t owe any tax. If you believe you weren’t required to file, you can contact HMRC to request they withdraw the notice to file. Once withdrawn, any late filing penalties will be automatically cancelled.
Yes, HMRC will consider a late return acceptable if it’s a ‘reasonable excuse’. For example, an unexpected stay in hospital, a fire, flood, or theft that prevented you from accessing your records.
You can use our calculator to estimate how much interest you’ll need to pay on the tax you owe if the deadline has passed. You can also contact HMRC directly, or speak to your accountant.
In this case, it’s best to contact HMRC as soon as possible. They might be able to set up a payment plan with you, such as a Time to Pay (TTP) agreement.
Even the most experienced business owners can struggle with their Self Assessment tax returns, so it can be very reassuring to have an accountant manage it for you! All our sole trader packages include your tax return as standard, helping you minimise the risk of missed deadlines or errors resulting in penalties.
Looking for more information?
We have a comprehensive range of free resources available
Deadlines and Penalties for Sole Traders
Learn more about the reporting deadlines you need to be aware of as a sole trader.
3 minutes
Quick Tax Saving Tips Guide
Our guide to helping you and your business save money and operate in the most tax efficient way possible.
2 minutes
Understanding Self Assessment
Vital information on registering and completing your Self Assessment, to keep you compliant with HMRC.
4 minutes
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