Pensions and Capital Gains Tax: How Pension Contributions Reduce CGT Bills

Capital Gains Tax and pension planning are usually discussed in isolation. This is a significant oversight. The rate of CGT you pay depends on whether your total taxable income (including the gain) falls within the basic-rate or higher-rate income tax band. A pension contribution reduces your taxable income — and can therefore determine whether a capital gain is taxed at 18% (basic rate) or 24% (higher rate). Following the 30 October 2024 changes, these 18%/24% rates apply to both residential property and other assets such as shares and funds. The saving on a large gain can dwarf the income tax relief on the pension contribution itself.

This guide explains the mechanics, provides worked examples, and identifies when the CGT-pension interaction is most valuable.

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How CGT Rates Work: The Band-Stacking Rules

Since 30 October 2024, the main CGT rates are the same for most assets — shares, investment funds, other financial instruments — and for residential property:

• 18% if the gain, when added to taxable income, falls within the basic-rate income tax band (i.e. taxable income plus gain does not exceed £50,270 in 2026/27)
• 24% for the portion of the gain (when stacked on top of income) above the basic-rate band limit

Before 30 October 2024, gains on assets other than residential property were taxed at the lower 10%/20% rates; those lower rates no longer apply. Residential property gains (above the private residence exemption) have been taxed at 18%/24% throughout.

Capital gains are always stacked on top of other taxable income when calculating the rate. This means:

• A person with taxable income of £45,000 and a capital gain of £30,000 has the first £5,270 of the gain (filling the band to £50,270) taxed at 18%, and the remaining £24,730 taxed at 24%
• If they had taxable income of £50,270 or above, the full £30,000 gain would be taxed at 24%
• If they had taxable income of £30,000, the full £20,270 of gain needed to fill the band (to £50,270) is at 18%, and only £9,730 is at 24%

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How Pension Contributions Alter the CGT Calculation

A pension contribution reduces adjusted net income (ANI) and, for the basic/higher-rate band test, effectively extends the basic-rate band by the gross amount of the contribution. HMRC's approach is that a pension contribution "extends" the basic-rate band for the taxpayer making it.

In practical terms:

• A higher-rate taxpayer who makes a £10,000 gross pension contribution has their effective basic-rate band extended to £60,270 (£50,270 + £10,000)
• Any capital gain stacked on top of their income now has an additional £10,000 of basic-rate band available

Worked example:

Emma has employment income of £55,000 in 2026/27. She sells shares realising a capital gain of £40,000, after using her annual CGT exempt amount (£3,000 in 2026/27). Without a pension contribution:

• Taxable income: £55,000 (gross) − £12,570 (personal allowance) = £42,430 within basic rate
• But earnings are £55,000, so £55,000 − £50,270 = £4,730 is already in the higher-rate band
• The full £40,000 capital gain is added on top of £55,000 income — all in the higher-rate band
• CGT rate: 24% on £40,000 = £9,600

Emma makes a £20,000 gross pension contribution (£16,000 net to SIPP, plus £4,000 basic-rate top-up):

• Her adjusted net income falls to £35,000 for band purposes
• Her effective basic-rate band extends to £50,270 + £20,000 = £70,270
• Of her £55,000 income, all falls within the extended basic-rate band
• The £40,000 capital gain is stacked on top: £55,000 + £40,000 = £95,000 total
• The basic-rate band (extended) covers up to £70,270 of income: leaving £24,730 of gain above it
• CGT: 18% × £15,270 (gain in basic rate) + 24% × £24,730 = £2,749 + £5,935 = £8,684

Pension contribution cost (net): £16,000 (after 20% basic-rate relief). Higher-rate relief on £20,000 gross: a further £4,000 on self-assessment (20% of £20,000). Net cost of pension contribution: £12,000.

CGT saving: £9,600 − £8,684 = £916

Total benefit: £4,000 (additional higher-rate income tax relief) + £916 (CGT saving) = £4,916 additional tax benefit from the pension contribution, beyond the basic-rate relief already received.

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When the Interaction Is Most Valuable

The CGT-pension interaction generates the most value when:

1. The gain is large and partly in the higher-rate band — a £5,000 gain well within the basic-rate band provides no opportunity. A £200,000 gain mostly in the 24% band creates a large saving opportunity.

2. The taxpayer's income is below £50,270 (or close to it) — the closer income is to the basic-rate band ceiling, the more pension contributions can push capital gains back into the 18% band.

3. The pension contribution can be structured efficiently — there is no point making a large pension contribution in a year when there is no significant capital gain. The planning must be co-ordinated across pension and investment decisions.

4. The differential is 6 percentage points — moving a gain from the 24% higher-rate band into the 18% basic-rate band saves 6p in the pound, for both residential property and other assets (the rates were aligned from 30 October 2024). For large gains in absolute terms, this 6-point saving can still be very substantial.

5. Business asset disposal in excess of BADR threshold — Business Asset Disposal Relief (formerly Entrepreneurs' Relief) provides a reduced CGT rate on the first £1 million of qualifying gains (18% for disposals in 2026/27, having risen from 10% via 14% in 2025/26). Gains above £1 million are taxed at 18%/24%. Pension contributions that reduce income and extend the basic-rate band can keep some of the non-BADR gain taxed at the 18% basic-rate CGT rate.

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Annual Allowance Constraint

The interaction is limited by the annual allowance (AA). The pension contribution must stay within the AA — standard AA of £60,000 per year, potentially enhanced by carry forward. For very large capital gains, a single year's AA may not be sufficient to shift all the gain into the basic-rate band.

Solution: spread the disposal over multiple tax years

Where the asset can be disposed of in stages (selling shares in tranches, for example), spreading the disposals across two or three tax years allows pension contributions to be made in each year, maximising the band-extension benefit over time.

Note: care must be taken not to trigger the bed-and-breakfast rules or associated securities rules when disposing of shares in stages within 30 days.

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Interaction with the Personal Allowance Trap (£100,000–£125,140)

A separate but related interaction occurs for taxpayers with adjusted net income between £100,000 and £125,140. In this range, the personal allowance is tapered — £1 of personal allowance is lost for every £2 of income above £100,000. The effective marginal income tax rate in this band is 60% (40% income tax on the additional income, plus 20% on the lost personal allowance).

A pension contribution that reduces adjusted net income below £100,000:

• Restores the full personal allowance (worth up to £2,514 in additional tax saving — 20% of £12,570)
• Reduces income into a zone where CGT band-extension rules apply more favourably

For individuals in the £100,000–£125,140 band with capital gains, a pension contribution can simultaneously restore the personal allowance AND push capital gains into the basic-rate CGT band. The combined effect can be exceptional.

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Interaction with Gifting and Gift Aid

A Gift Aid donation to charity has the same band-extension effect as a pension contribution for CGT purposes. Both operate by extending the higher-rate threshold. A taxpayer who is charitably inclined can therefore achieve the same CGT saving through charitable giving as through pension contributions — while also generating income tax relief and (potentially) IHT benefits through charity gifts.

The two mechanisms are additive: a £10,000 pension contribution and a £5,000 Gift Aid donation together extend the band by £15,000. For those with philanthropic intent alongside capital events, this combination can be powerful.

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IHT Interaction: The Future Planning Perspective

From April 2027, pension assets are expected to be brought within the estate for Inheritance Tax purposes (subject to legislative confirmation). This changes the calculus for pension vs other tax-efficient wrappers somewhat. However, the CGT-pension interaction remains a valid planning tool for the current year's tax position, regardless of what happens to pension IHT treatment in future.

For those concerned about pension assets forming part of the IHT estate, channelling capital gains tax savings into ISAs (rather than additional pension contributions) may be preferable from an estate planning perspective — ISAs are within the IHT estate but assets can be nominated more freely. The decision depends on the relative weight given to current-year CGT saving versus long-term estate planning.

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Practical Steps

1. Identify your expected capital gains for the tax year — estimated sale proceeds minus acquisition cost and reliefs.
2. Calculate your taxable income — employment income, self-employment profit, rental income, pension income, minus personal allowance.
3. Determine how much of the gain is taxed above the basic-rate band — this is the saving opportunity.
4. Calculate the gross pension contribution needed to push income + gain below the higher-rate threshold.
5. Check the annual allowance — include employer contributions in the total and compare against available AA (including carry forward).
6. Make the contribution before 5 April — relief applies to the tax year in which the contribution is received by the pension scheme.
7. Claim higher-rate relief on self-assessment — include the pension contribution on the self-assessment return, and HMRC will extend your basic-rate band and calculate the CGT accordingly.

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Compliance Caveats

CGT rates, income tax bands, annual allowances, and the personal allowance taper all change with each Budget and Finance Act. The rates and examples in this guide reflect the position as understood for 2026/27. Future changes — including potential CGT rate increases or further pension reform — may alter the planning landscape. This guide does not constitute regulated financial or tax advice. Before making significant pension contributions in a year of capital disposal, seek advice from a chartered accountant or tax adviser who can model your specific position accurately.

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How Global Investments Can Help

For HNW investors managing significant investment portfolios, business exit events, or property disposals alongside pension planning, the CGT-pension interaction is often the most valuable tax planning opportunity available in a given year. Global Investments advises clients on co-ordinating capital event planning with pension contributions, ISA utilisation, and broader wealth structuring. Contact our team to discuss how we can help you capture this often-overlooked opportunity.