A client has a £15,000 gain on shares: the £3,000 allowance, 18% or 24%, and what spreading it over five years saves

At an annual review, the question comes up most often with a client who bought a fund or some shares outside an ISA years ago. It is now worth £15,000 more than they paid. They would like to rebalance, or put the money into their ISA, and ask what it will cost. The sum is short, and it changes with how the sale is timed.

The figures on GOV.UK

For the 2026 to 2027 tax year the Capital Gains Tax annual exempt amount is £3,000. The page states the rates from 6 April 2026 as 18% where the person's combined taxable income and gains stay within the basic Income Tax band, and 24% on gains above it or for higher and additional rate taxpayers.

The page I read does not give separate rows for shares and residential property, so this guide uses the two rates as the page states them and assumes the asset is a fund or shares. If the client's gain is on a second home, check the property page before you quote.

One disposal against five

A single client with a £15,000 gain.

The saving is the whole bill. It is £2,160 for a basic rate client and £2,880 for a higher rate client. That figure is before any change in the price over the five years, which the table cannot know. A spread means the client carries the market risk on the unsold part, and a falling market erases the gain it was meant to protect.

The usual extra moves

• The couple. A married couple each have an allowance. Where the asset is jointly held or transferred between them, £6,000 a year can be realised tax-free. The page I read does not set out the rules on transfers between spouses, so confirm them before acting.
• The ISA. Selling the holding and buying it back inside an ISA is often called a bed and ISA. The gain is taxed as above on the sale, and growth afterwards is outside the charge. The yearly ISA allowance is a separate limit; our note on the cash ISA limit changes from April 2027 covers the cash side of it.
• The tax year end. The allowance is use-it-or-lose-it each year. A client who realises £3,000 on 5 April and another £3,000 on 6 April has used two years' allowance.

What to ask at the review

1. What did it cost, and what is it worth? The gain is the difference after costs, so a record of the purchase price is needed.
2. Is there other income? The 18% and 24% depend on where the gain falls against the client's other taxable income, so the rate is the client's, not the product's.
3. Does the client want the exposure? Tax is one input to a review decision, not the only one. The reasons for a sale go on the file; see our annual review checklist.
4. Is the pension a better home for new money? The carry forward guide shows how much unused allowance a client may have.

I did not read the rules on losses, on reporting a disposal to HMRC or on the matching rules that apply to buying the same holding back within 30 days. Each can change what a client pays, so read them before you advise.

Overlyft builds AI staff who join your advice team, list each client's holdings outside wrappers with the purchase cost from the file, work out the gain and the tax at both rates and prepare a note for the adviser to check before the review.

This is general information, not tax or investment advice. Check GOV.UK and the client's own figures before you advise.