SIP Shares and Capital Gains Tax: What Happens After Withdrawal

July 16, 2026

The Share Incentive Plan calculator models Income Tax and National Insurance treatment by holding period, but Capital Gains Tax is a separate consideration that only comes into play after shares leave the SIP trust.

Step 1 — Understand CGT Only Applies to Growth After Removal

Income Tax and National Insurance (the tax the calculator projects) apply to the shares’ value at the point they leave the trust, based on your holding period. Capital Gains Tax is a separate, later consideration — it only applies to any further growth in the shares’ value after they’ve left the trust, if and when you eventually sell them.

Step 2 — Selling Shares Directly From the Trust Avoids CGT Entirely

If shares are sold while still inside the SIP trust (rather than withdrawn and then sold separately), there’s no Capital Gains Tax at all on that sale — this is one of the cleanest ways to realize value from SIP shares without a separate CGT event.

Step 3 — Transfer to an ISA Within 90 Days to Avoid CGT

Shares withdrawn from the trust can be transferred into a Stocks and Shares ISA within 90 days of removal without triggering Capital Gains Tax on the transfer itself, and any future growth inside the ISA remains fully tax-free going forward. This transfer counts toward your annual £20,000 ISA contribution allowance for that tax year — a real constraint if the value of your SIP shares is large relative to your remaining ISA headroom for the year.

Step 4 — Understand What Happens If You Miss the 90-Day Window

If shares aren’t sold from the trust or transferred to an ISA within 90 days of withdrawal, they’re held as ordinary shares outside any tax wrapper — any gain from that point forward (measured from the market value at withdrawal, not the original award value) is subject to standard Capital Gains Tax rules if and when you sell.

Step 5 — Know the 2025/26 Annual CGT Exempt Amount

For the 2025/26 tax year, individuals have an annual Capital Gains Tax exempt amount of £3,000 — gains up to this threshold across all your capital gains for the year (not just SIP shares) aren’t taxed at all. Gains above this threshold are taxed at your applicable CGT rate, which depends on your overall income tax band.

Step 6 — Combine Strategies Across Multiple Tax Years

If a share sale would push gains meaningfully above the annual exempt amount, spreading sales across more than one tax year — using each year’s exempt amount separately — can reduce or eliminate the CGT owed compared to selling everything at once. This requires planning ahead of a sale, not something that can be applied retroactively after the fact.

A Worked Example

Shares worth £5,000 at SIP withdrawal grow to £8,000 by the time they’re sold two years later, held outside an ISA (the 90-day window was missed):

Capital gain = £8,000 − £5,000 = £3,000
Annual CGT exempt amount (2025/26) = £3,000
Taxable gain = £3,000 − £3,000 = £0

In this specific case, the gain happens to fall entirely within the annual exempt amount, so no CGT is owed — but a larger gain, or other capital gains realized the same tax year, would reduce or eliminate this shelter.

Get Specific Advice for Your Situation

CGT rates, the annual exempt amount, and ISA rules can all change between tax years, and your specific circumstances (other capital gains, income tax band, timing of a sale) affect the actual tax owed. Confirm current rules against HMRC’s official guidance or a qualified tax adviser before making a decision based on this guide — see the SIP terms glossary for the related Income Tax/NIC holding-period rules the Share Incentive Plan calculator does model directly.