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Self Assessment late penalty calculator (2025/26 return)

The online deadline for the 2025/26 tax return is 31 January 2027, and any tax owed is due the same day. Enter what you owe and when you filed or paid (or will) to see the penalties and interest, and the dates that make it more expensive.

£100a day late
£10/dayafter 3 months
5%unpaid tax at 30 days
Last updated

Calculator

For online returns for the 2025/26 tax year (6 April 2025 to 5 April 2026) under the current penalty rules. Leave a date blank if you haven’t filed or paid yet.

£
Enter £0 if you don’t owe anything: the late filing penalties still apply.
Blank = not filed yet.
Blank = not paid yet.

Settings

Used for anything not filed or paid yet. Defaults to today.
%
Bank of England base rate + 4%. Check HMRC’s current rate.
Your penalties show here.Enter what you owe and press Calculate. After that, it updates as you change anything.
Updates as you type
Estimated penalties and interest
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Total penalties and interest

Breakdown

Dates to act by

    Estimates only, assuming the whole amount stays unpaid until the payment date and no payments on account are involved. HMRC may cancel penalties if you have a reasonable excuse.

    Self Assessment penalties for late filing

    How latePenaltyFor the 2025/26 return
    1 day£100, even if you owe no taxFiled after 31 January 2027
    3 months£10 a day, up to 90 days (£900)From 1 May 2027
    6 months£300 or 5% of the tax due, whichever is moreNot filed by 31 July 2027
    12 monthsAnother £300 or 5% of the tax due, whichever is moreNot filed by 31 January 2028

    Penalties for paying late

    Tax still unpaid atPenalty
    30 days after the deadline5% of the unpaid tax
    6 monthsAnother 5% of the unpaid tax
    12 monthsAnother 5% of the unpaid tax

    HMRC also charges interest on tax paid late, from the day after the deadline until you pay. The rate is the Bank of England base rate plus 4%, so it changes when the base rate does.

    What to do if you’ve missed the deadline

    1. File as soon as you can. The £100 penalty applies straight away, but the daily penalties only start after 3 months.
    2. Pay what you can now. Interest and the 5% penalties are based on what’s still unpaid, so paying part of it reduces them.
    3. Can’t pay in full? You may be able to set up a Time to Pay payment plan with HMRC.
    4. Had a reasonable excuse? For example a serious illness or a bereavement. You can appeal a penalty within 30 days of the penalty notice.

    From the 2027/28 tax year, and earlier for people already using Making Tax Digital for Income Tax, a points-based system replaces these late filing penalties. This calculator uses the rules that apply to most people’s 2025/26 return.

    FAQ

    What is the penalty for filing a Self Assessment tax return late?

    £100 as soon as it’s late, even if you owe no tax. After 3 months, £10 a day for up to 90 days. After 6 months and again after 12 months, the greater of £300 or 5% of the tax due.

    When is the Self Assessment deadline for 2025/26?

    31 January 2027 for online returns, and the tax you owe is due the same day. The paper deadline was 31 October 2026.

    Do I get a penalty if I don’t owe any tax?

    Yes, the £100 late filing penalty and the daily penalties still apply. The 5% penalties are at least £300 each, whatever the tax due.

    Can I appeal a Self Assessment late penalty?

    Yes, if you had a reasonable excuse, such as serious illness or the death of a close relative, and you filed as soon as you could afterwards. Appeal within 30 days of the date on the penalty notice.

    Official guidance