Fixed Savings Bonds Maturing This Autumn? Why All Multi-Year Interest Is Taxed in One Tax Year

Savers who locked into two- or three-year fixed-rate savings bonds (Outside of an ISA) are seeing those accounts mature in autumn 2026 — and many are being caught out by a strict HMRC tax rule: savings interest is taxed in the tax year you can actually access it, not spread across the years it was earned.

How the "arising basis" traps multi-year fixed bonds

Under HMRC's Savings and Investment Manual rules, interest only counts toward your Personal Savings Allowance (PSA) when it becomes accessible to you:

• Personal Savings Allowance (2026/27): £1,000 tax-free interest for basic-rate (20%) taxpayers; £500 for higher-rate (40%) taxpayers; and £0 for additional-rate (45%) taxpayers.
• The multi-year bond problem: Suppose a higher-rate taxpayer put £15,000 into a 3-year fixed-rate bond in October 2023 paying 5.2% compound interest at maturity, with no access to the interest until the 3-year term ends in October 2026. Over three years, the bond generates roughly £2,464 in total interest.
• Because the saver couldn't withdraw the interest in years 1 and 2, HMRC treats the entire £2,464 as landing in the 2026/27 tax year — breaching their £500 PSA by £1,964 and triggering a £785.60 tax bill at 40%, even though the annualised interest (~£821/year) was much smaller.

How HMRC automatically adjusts your PAYE tax code

You don't have to file a Self Assessment return for HMRC to spot savings interest (unless your total income from savings and investments exceeds £10,000). Every UK bank and building society automatically reports the total non-ISA interest paid to you after 5 April each year directly to HMRC.

HMRC then collects the tax owed by reducing your PAYE tax code on your salary or private pension — often estimating that you will earn the same amount of interest again in the following year, which can temporarily double the deduction on your monthly payslip unless you log into your Personal Tax Account to correct their estimate.

Checklist: how to avoid the multi-year interest spike

• When choosing a multi-year fixed-rate savings bond outside an ISA, opt for an account that pays interest out annually (or monthly) into a separate nominated current/savings account you can access — that way, each year's interest is taxed in the year it is paid rather than rolled up into one big maturity spike.
• Use your £20,000 ISA allowance before 5 April 2027 (remembering the Cash ISA cap for under-65s drops to £12,000 from 6 April 2027).
• If one partner is a non-taxpayer or earns under £17,570 in wages/pensions, make sure savings are held in their name so they can benefit from the £5,000 Starting Rate for Savings on top of the £12,570 Personal Allowance and £1,000 PSA (up to £18,570 completely tax-free).
• Check your HMRC Personal Tax Account if a multi-year bond matures this year so HMRC doesn't assume a one-off 3-year maturity payout will repeat next year.

How the UK compares internationally

Taxing rolled-up interest only at maturity differs from the US approach. In the United States, the IRS applies "Original Issue Discount" (OID) and constructive receipt rules to multi-year certificates of deposit (CDs), generally requiring savers to declare and pay tax on the accrued interest every single year via Form 1099-INT even if the money remains locked in the CD.

Key Numbers

• Personal Savings Allowance (basic / higher / additional rate): £1,000 / £500 / £0
• Starting Rate for Savings (for low non-savings income under £17,570): up to £5,000 at 0%
• Threshold where savings/investment income requires Self Assessment: £10,000 or more
• Maximum tax-free income combining Personal Allowance + Starting Rate + PSA: £18,570

Sources

• Tax on savings interest: Personal Savings Allowance and Starting Rate — GOV.UK
• Personal tax account: sign in or set up — GOV.UK
• Topic no. 403, Interest received — US Internal Revenue Service (IRS)

Educational content only — not financial advice.