Fixed-rate savings bonds that "pay interest at maturity" (no annual credit, all interest paid at the end of the term) are taxed by HMRC when the interest is paid to you, not when it's earned. So a 5-year bond paying £8,000 of accumulated interest at maturity is taxed as £8,000 of interest in the maturity year — likely blowing past your £1,000 PSA and possibly pushing you into higher-rate. Bonds with annual interest credits are taxed each year — the safer option for PSA-sensitive savers.
The two accounting types
UK savings bonds operate on one of two interest-payment models:
- Annual interest credit (or annual gross interest "added to your account"): interest accrues each year and is credited to your balance. HMRC taxes the interest in the year it accrues — even if you can't withdraw it yet.
- Interest paid at maturity: interest accrues but is paid in one lump at the end of the term. HMRC taxes the full lump in the maturity year.
For the same nominal interest rate, the second model can create dramatically higher tax bills due to bunching.
Worked example — the tax shock
£100,000 in a 5-year fixed-rate bond at 4.5% AER, interest paid at maturity
| Total interest paid at maturity (year 5) | ~£24,618 |
| Saver's other income year 5: £50,000 salary | |
| Personal Allowance + basic rate band fully used by salary | |
| Interest taxed entirely in year 5 | £24,618 |
| PSA (higher-rate threshold crossed) | £500 |
| Taxable interest | £24,118 |
| Tax: £24,118 × 40% | £9,647 |
Compare with an annually-paying bond: ~£4,924 of interest each year for 5 years. The PSA (£500 higher rate) reduces taxable to £4,424. Tax: £1,770/year × 5 = £8,848. Total tax over 5 years: £8,848 vs £9,647 — the lump-at-maturity bond costs £799 more in tax just from band-shoving.
The "year of maturity" income spike
The biggest concern isn't just the headline tax bill — it's the secondary effects of pushing income up in one year:
- HICBC clawback. If you have children and the maturity interest pushes ANI above £60k, you owe HICBC for that year.
- 60% trap. ANI crossing £100k tapers Personal Allowance, creating a 62% marginal rate on the interest above £100k.
- Tapered pension annual allowance. Adjusted income crossing £260k restricts your pension contribution capacity.
- Marriage Allowance lost. If you cross higher rate due to the bond, your Marriage Allowance is gone for that year.
- Tax credits + Universal Credit (if relevant). The spike year can drastically alter entitlement.
How HMRC actually determines "when interest counts"
HMRC's rule depends on the bond's terms. The test:
- If the saver has a right to withdraw or claim interest annually — the interest is taxed each year as it accrues.
- If the saver has NO right to access interest until maturity — the interest is taxed in full in the maturity year (Schedule 4, Income Tax (Trading and Other Income) Act 2005).
Practical test: does your bond's annual statement show interest "added" to your balance with the option to withdraw it? If yes, annual accounting applies. If the bond just compounds invisibly until maturity, year-of-maturity accounting applies.
How to avoid the trap
- Choose annually-paying bonds. Many providers offer the same rate with annual interest credit. Pick those over "interest at maturity."
- Split across multiple shorter bonds. Five 1-year bonds rolling over have interest paid each year, spreading the tax.
- Use Cash ISA for large sums. No PSA constraint, all interest tax-free, FSCS-protected up to £120k per banking group.
- Time the maturity in a lower-income year. If you can choose a 3 or 5-year term, schedule the maturity for a year when you're not earning (career break, retirement).
- Spread across joint accounts. Married couples can hold the bond jointly — interest splits 50/50, each using their own PSA.
Premium Bonds — the alternative
Premium Bonds prizes are tax-free, with no PSA constraint. Effective rate ~4.4% (2026/27 prize fund rate). Variance is high — small holdings rarely win — but for £20,000+ holdings the distribution is reasonable. See the Premium Bonds guide.
Sources and methodology
The rules on when interest counts follow HMRC's Savings and Investment Manual, in particular SAIM2000 onwards. For a personalised calculation, see the savings interest calculator. The methodology page documents sources.
Related guides
How UK Tax Drag holds itself to account
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