Onshore vs offshore bonds: how top-slicing relief differs

Both bond types run the same five-step top-slicing computation (ITTOIA 2005 s.535–537; IPTM3820) — and, under ITTOIA 2005 s.531(1)'s express carve-out, both get the same basic-rate “deemed tax paid” credit within that relief calculation. The difference lands one level down, in the member's REAL final liability. An onshore bond's life fund has already borne tax inside the fund, so the individual is treated as having paid basic-rate tax on the gain generally — a 20% credit against the actual tax bill for 2026/27. From 6 April 2027 bond gains, as savings income, are taxed at 22%, 42% and 47%, and the credit becomes the savings basic rate of 22% (Finance Act 2026 s.5; ITTOIA 2005 s.530(1) as amended). An offshore bond's fund rolls up gross: s.531(1) lets the SAME credit reduce the relief calculation, but it does not carry through to reduce what the individual actually pays.

The credit, on a concrete gain

Take the offshore case the top-slicing articles use: a £60,000 gain before any TAR over six complete years (slice £10,000), £35,000 of other income, 2025/26 (the figures are the same for 2026/27). Both bond types carry a basic-rate credit of 20% — £12,000 — inside the relief calculation, restricted to the gain less any unused personal allowance (a no-op here). Only the ONSHORE bond gets to deduct that same £12,000 from its real, final liability.

Worked-example basis: No time-apportioned reduction is due for any gain or policy shown. TAR is not calculated or applied. Raw gains are shown before any TAR.

The credit is notional: treated as paid, never repayable. A non-taxpayer cannot reclaim it. On this exact case, both bond types now print the SAME top-slicing relief figure — £8,846 — because the relief calculation is credited identically. What changes is the final net tax: onshore, the £12,000 credit also reduces the real liability the relief is subtracted from, and the member pays £0 additional tax; offshore, the real liability stays uncredited, and the member pays £12,000. The same relief in both tax computations, with different amounts payable. The insurer’s certificate does not calculate the individual’s relief.

The common error

The mistake used to be assuming offshore gains get no credit anywhere — understating the relief figure itself. The corrected trap is the opposite: assuming that because the RELIEF figures now match, the NET TAX must match too. It does not. The credit that reduces the real, final liability is onshore-only; the credit inside the relief calculation applies to both. The onshore credit can cover basic-rate tax that would remain payable on an otherwise identical uncredited offshore gain. It cannot generate a repayment: credit left over after the year’s whole income tax, including tax on other income, cannot be reclaimed. A client’s tax band before the gain is added does not settle either final liability.

The top-slicing relief calculator takes the bond type and applies each credit on the right side of the computation; start on the chargeable event gain calculator first if you are working from the certificate figures. The final net tax for each bond type, where no TAR is due, is on the onshore bond tax calculator and the offshore bond tax calculator; the five steps themselves are set out in how top-slicing relief works.

ITTOIA 2005 s.530 (basic-rate credit) · s.531(1) (offshore relief-calculation carve-out) · IPTM3810 (credit for UK policies ; none for foreign policies) · IPTM3830 (basic rate deducted inside the relief calculation for foreign policies) · IPTM3820 (top-slicing) · Finance Act 2026 s.5 (2027/28 savings rates)