Do I Need to Do a Self Assessment for Savings Interest?

Tax Queen

Tax Expert @ Pie

4 min read

Do You Need a Self Assessment for Savings Interest?

Usually not, unless you already file a Self Assessment return or your untaxed savings and investment income is £10,000 or more (HMRC may also ask you to file). This £10,000 test is separate from your tax-free allowance and is measured before allowances. For most people, HMRC collects any tax due on interest above their allowance through their tax code or a simple bill.

With savings rates staying high, more people are going over their tax-free allowance for the first time. Here is how it works in plain English.

How Tax on Savings Interest Works

Most people can earn some interest tax-free each year thanks to the Personal Savings Allowance. In 2026/27 it is £1,000 for basic rate taxpayers and £500 for higher rate taxpayers. Additional rate taxpayers don't get one.

Some people on low incomes can also use the savings starting rate, which lets extra interest go untaxed. You can read more in our guide to the Personal Savings Allowance and tax-free interest.

Interest above your allowance is taxed at your normal rate: 20%, 40% or 45% in England, Wales and Northern Ireland. Interest in an ISA is always tax-free and does not use up your allowance.

When HMRC Sorts It for You

Banks and building societies tell HMRC how much interest they pay you each year. If you are employed or get a pension and don't file a return, HMRC normally adjusts your tax code to collect what you owe.

If that isn't possible, HMRC may send you a letter called a Simple Assessment, which is a bill showing what you owe and how to pay. You don't need to do anything until you receive it, but do check the figures are right.

When You Must File a Self Assessment

You must tell HMRC about your interest through Self Assessment if:

You already file a return, for example as a sole trader or landlord. All taxable interest goes on it.
Your interest is over £10,000 in a tax year. You must register by 5 October after the end of that tax year.
HMRC asks you to file by sending a notice to complete a return.

If you need to sign up, our guide on how to register for Self Assessment with a Government Gateway login walks you through it step by step.

Key Dates to Remember

Interest earned in 2025/26 goes on the online return due 31 January 2027, along with any tax owed. Interest from 2026/27 goes on the return due 31 January 2028.

Miss the filing deadline and there is a £100 penalty straight away, with more after 3 months.

Common Worries and Mistakes

In online communities, many savers worry they have broken the rules by not reporting interest. If your interest is under £10,000 and you don’t file a return, HMRC will usually adjust your tax code or send a Simple Assessment. If you think you owe tax and haven’t heard, contact HMRC.

A frequent mistake is thinking only interest you withdraw counts. Interest is taxed in the tax year it is paid or credited to your account, even if you leave it there.

Fixed-term bonds cause confusion too. If all the interest is paid when the bond ends, it is usually taxed in that one year, which can push you over your allowance unexpectedly.

Self-employed people and landlords sometimes forget that interest has no tax taken off at source. This can push your Self Assessment bill to £1,000 or more and trigger payments on account, which are advance payments due on 31 January and 31 July.

Others forget that joint account interest is usually split equally between account holders. Each person reports their own share.

What to Do Next

Gather your annual interest statements from every bank and building society.
Leave out ISA interest, as it is tax-free.
Check your tax code or any HMRC letter for the right interest figures.
If you file a return, add your interest before 31 January 2027.

If you are unsure about any of this, our article on how to get help with Self Assessment in the UK explains where to turn.

Make It Easy with Pie Tax

Pie Tax tracks your income and expenses, sorts your expenses automatically and gives you a real-time tax estimate, so interest never catches you out. It also sends your MTD quarterly updates and Self Assessment returns straight to HMRC.

Try Pie Tax for free and take the stress out of tax season.