The Personal Savings Allowance: Why Your Interest Suddenly Became Taxable

Two things changed at once when the Personal Savings Allowance was introduced, and the second is what causes the confusion. Banks stopped deducting tax from interest, so it is paid gross. And a slice of interest became tax free depending on your rate band. The result is that many people saw tax disappear from their savings entirely, concluded interest was untaxed, and have been surprised at intervals ever since.

The Allowance by Band

Interest above the allowance is taxed at your marginal rate. The allowance is not a deduction from income — it taxes a slice at 0% rather than removing it — which matters because that slice still counts towards your total income for other purposes.

Why the Tax Arrives Late

Since banks pay interest gross, nothing is collected at source. Banks report interest to HMRC after the tax year ends, HMRC compares it with your record, and then collects. For people outside Self Assessment the usual mechanisms are a P800 calculation or an adjustment to next year's tax code — which means tax on interest earned in one year is often collected through a lower tax code a year or more later.

That lag is why a coding notice can show an unexplained deduction for savings income you had forgotten about, and why a year of high interest rates produces tax bills long after rates have fallen.

What Is Not Covered

• ISAs are outside the allowance entirely because the interest is not taxable in the first place — using the £20,000 ISA allowance is the cleanest way to keep interest out of charge.
• Dividends have their own separate allowance and their own rates.
• Premium Bond prizes are not interest and are not taxable.
• Joint accounts are normally split equally between the holders, each using their own allowance.
• Fixed-term accounts can be taxable in the year interest becomes accessible, which for a multi-year bond can bunch several years of interest into one tax year.

The Bunching Problem

The last of those is worth dwelling on. A three-year fixed bond paying all its interest at maturity can produce a single year in which interest far exceeds the allowance, even though the annual amount was modest. Someone close to a band threshold can find that one maturity pushes them over it. Where the choice exists, annual-interest accounts spread the income; where it does not, the maturity date is worth knowing in advance.

Practical Steps

1. Add up interest across all accounts, not just the largest, and include joint accounts at your share.
2. Use the ISA allowance first for money that will produce meaningful interest.
3. Check your tax code for a savings income adjustment, and correct it if the estimate is wrong — see how tax codes work.
4. Consider whose name accounts are in. Interest belongs to the account holder, and a couple in different bands may have very different allowances available.
5. Watch pension contributions, which extend your basic rate band and can therefore change which allowance applies to you.

If You Live Abroad

Non-residents are in a different position: UK bank interest is UK-source, generally paid gross, and often falls outside UK tax under the rules for disregarded income — though the interaction with the personal allowance is intricate. Our guide to UK tax while living abroad covers it, and the practical point is that your country of residence will usually tax it instead.

Frequently Asked Questions

How much savings interest can I earn tax free?

£1,000 if you are a basic-rate taxpayer, £500 if higher rate, and nothing at all if you pay the additional rate. Interest above the allowance is taxed at your marginal rate.

Why did HMRC send me a bill for savings interest?

Because banks pay interest gross and report it to HMRC after the year ends. The tax is then collected through a P800 calculation or an adjustment to a later tax code, which is why it arrives long after the interest was earned.

Does ISA interest count towards the allowance?

No. ISA interest is not taxable at all, so it sits entirely outside the allowance. Using the £20,000 ISA allowance is the simplest way to keep interest out of charge.

What happens with a fixed-term bond?

Interest can be taxable in the year it becomes accessible, so a multi-year bond paying at maturity may bunch several years of interest into one tax year and exceed the allowance.

Related Guides

Keep reading with these related guides and calculators:

• Bed and ISA — moving holdings into a wrapper
• The P800 calculation — how the tax gets collected
• How tax codes work — the savings adjustment in your code
• UK tax living abroad — interest as a non-resident
• Savings accounts — where the interest comes from
• Savings calculator — what a pot earns