Top slicing relief reduces the income tax on a chargeable event gain from an investment bond by working out the tax as if the gain had been spread evenly over the years the policy has run. HMRC taxes one annual slice at your marginal rates, multiplies that tax by the number of complete years, and gives the difference as a tax reduction. It helps where the gain pushes you into a higher band; it is only available to individuals, and the full gain still goes on the return.

What problem does top slicing relief solve?

A chargeable event gain is taxed when it is realised, not as it builds up. HMRC acknowledges at IPTM3820 that this can disadvantage people when growth that accrued over many years is all charged in a single tax year. A basic rate taxpayer surrendering a bond can find most of the gain taxed at 40% simply because it arrives in one lump. Top slicing relief, in sections 535 to 537 of the Income Tax (Trading and Other Income) Act 2005, corrects for that.

The relief is given as a reduction in tax, not a reduction in the gain. IPTM3840 warns that a common misconception is to enter the gain divided by the number of years on the tax return; the full gain must be returned, and HMRC calculates the relief when the gain is reported through Self Assessment (HS320).

Who can claim it?

Only individuals. IPTM3820 states that the relief is not available to companies, trustees or personal representatives. It is generally useful when:

  • your other income is taxed at the basic rate but adding the gain takes you into the higher or additional rate; or
  • your other income is taxed at the higher rate but adding the gain takes you into the additional rate.

HMRC adds that some relief can arise even when the gain does not cross a band, because of the way the Personal Savings Allowance and the starting rate for savings are recalculated.

How is the number of years (N) worked out?

N is the number of complete years used to slice the gain, and IPTM3830 says it can never be less than 1. The starting point depends on the event:

Event Where N starts
Full surrender, maturity or death (final events) Commencement of the policy
Excess event or other part surrender gain, UK policy, policyholder always UK resident The later of commencement and the last previous calculation event
Offshore policy issued before 6 April 2013, part surrender gain Commencement of the policy
Personal portfolio bond annual gain No relief; N is entered as 1

The practical effect is that a gain on a second excess event on a UK bond is sliced only over the years since the first, so it gets less relief than a full surrender gain of the same size.

Time apportionment for periods abroad

If you were not UK resident for part of the time you held the policy, a time apportioned reduction may cut the gain by the fraction of foreign days in the period you held it (HS320 and IPTM3730 onwards). Where that applies, N is also reduced by the whole number of years you were not UK resident. HMRC’s example at IPTM3830 has a policy taken out in 2014, two years of Irish residence, and a full surrender in 2022: N is 8 years less 2, so 6. HS320 sets the order as restricted relief qualifying policy reduction first, then time apportionment, then top slicing relief.

What changed in the calculation from 2018 to 2019?

The top slicing calculation is a separate notional calculation, and recent changes made it more generous (IPTM3820):

  • Personal Allowance. For gains arising in 2018 to 2019 onwards, the Personal Allowance in the relief calculation is worked out with only the slice included in income. Someone whose full gain took income over £100,000 and tapered away their allowance can get it back in the relief calculation. The full gain still counts in the main calculation, so see Personal Allowance tapering.
  • Savings bands. For gains arising in 2021 to 2022 onwards, the Personal Savings Allowance and starting rate for savings are also recalculated using the slice.
  • Ordering. Reliefs and allowances are set against other income before the slice, and lease premiums and employment termination payments are ignored when working out total income for the relief calculation.

How is the relief calculated, step by step?

For a single gain, IPTM3840 sets out five steps:

  1. Work out total taxable income including the full gain, and which bands the gain falls into.
  2. Calculate tax on the gain and deduct basic rate tax treated as paid. This is the total liability.
  3. Divide the gain by N to get the annual equivalent.
  4. Calculate tax on the annual equivalent as if it were the only gain, deduct basic rate tax treated as paid on it, and multiply by N. This is the total relieved liability.
  5. Top slicing relief is step 2 minus step 4.

For offshore bonds, IPTM3830 explains that basic rate tax treated as paid is still deducted in both the liability and relieved liability figures for this purpose, so the relief is computed in the same way as for a UK bond even though no actual credit is given against the tax bill.

A worked calculation

Illustration only. In the 2026 to 2027 tax year Jo has employment income of £48,000 and fully surrenders a UK bond held for 5 complete years, producing a gain of £40,000. The Personal Allowance is £12,570 and the basic rate band is £37,700.

Step 1 and 2: tax on the full gain. Taxable employment income is £35,430, leaving £2,270 of basic rate band. Jo is a higher rate taxpayer, so the Personal Savings Allowance is £500.

Slice of the £40,000 gain Rate Tax
£500 0% (Personal Savings Allowance) £0
£1,770 20% £354
£37,730 40% £15,092
Total £15,446

Less basic rate tax treated as paid of £8,000 (20% of £40,000) gives a total liability of £7,446.

Step 3: annual equivalent. £40,000 divided by 5 is £8,000.

Step 4: tax on the slice. With only £8,000 added, Jo’s taxable income is £43,430, still in the higher rate band, so the Personal Savings Allowance stays at £500. The slice is taxed as £500 at 0%, £1,770 at 20% (£354) and £5,730 at 40% (£2,292), a total of £2,646. Less £1,600 treated as paid on the slice leaves £1,046. Multiplied by 5, the total relieved liability is £5,230.

Step 5: relief. £7,446 less £5,230 gives top slicing relief of £2,216. Jo pays £5,230 on the gain instead of £7,446.

HMRC’s own example at IPTM3850, using 2022 to 2023 figures, shows the Personal Allowance effect: £50,000 of employment income plus a £150,000 gain removes the allowance in the main calculation, but the relief calculation restores it because income with only the £30,000 slice is £80,000. The relief in that example is £3,500.

What if there are two or more gains in a year?

Under section 537 and IPTM3840, the gains are added together in steps 1 and 2. Each gain is divided by its own N and the results are added to give a total annual equivalent. The tax on that total, less the notional credit, is multiplied by the total gains and divided by the total annual equivalent to get the relieved liability.

Where does top slicing relief not help, and what goes wrong?

  • Means tested figures. IPTM3820 confirms there is no top slicing when working out income for age related allowances and tax credits; the full gain counts. HMRC’s IPTM3597 example of a large part surrender also lists the withdrawal of child benefit as part of the cost (see the High Income Child Benefit Charge).
  • Trustees and estates. Gains taxed on trustees or personal representatives get no relief.
  • Short N on excess events. Large withdrawals create gains sliced over few years; see the 5% withdrawal rule.
  • Wrong entries. Entering the slice rather than the full gain, or the wrong number of years. The certificate from the insurer should state the complete years.

From 2027 to 2028 the savings rates rise to 22%, 42% and 47% under measures announced at Budget 2025, which will change the figures in any relief calculation for gains arising from 6 April 2027.

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Sources

Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 8 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.