Tax and Legal

Fast matching rule for shares in UK Capital Gains Tax

By Walid Mograbi · 2026-07-28 · 2 min read

When you buy shares of the same company and class in several lots, UK CGT uses the Section 104 pooling approach. This lesson explains the matching order on disposal and how to remove pool cost when only part of the holding is sold.

Quick matching rule for shares under UK CGT

Core principle

For the same class of shares in the same company, all shares are grouped into one Section 104 pool. Inside that pool, every share is treated as carrying the same pooled acquisition cost.

Disposal matching order

When disposing of shares, match in this sequence:

• First: shares sold and bought on the same day.
• Then: shares bought in the 30 days after the sale (for UK tax residents).
• Finally: shares from the Section 104 pool.

Partial disposal allocation

If you sell only part of your holding, deduct only the proportionate cost from the pooled total.

Use this ratio: pool cost × (shares sold ÷ total shares in pool).

Practical checklist

• Confirm shares are in the same class and company.
• Record purchase and sale events in chronological order.
• Apply same-day matching first.
• Apply 30-day post-sale matching second (if applicable).
• Match the remaining shares against the Section 104 pool.
• For partial sales, reduce only the proportional part of pool cost, not the full pool value at once.
• Review the result before calculating gain or loss for the disposal period.

How this helps in practice

Following the rule in this order prevents chaotic calculations when you have multiple purchase lots and supports cleaner CGT reporting by reducing cost mistakes.

Visual flow summary

From lot purchases to a partial sale: how cost is distributed

1. Aggregate similar shares into the Section 104 pool.
2. Match disposal shares in order: same-day, then 30 days, then pool.
3. For partial disposal, allocate cost by proportion of pool sold.

Warning

The general rules do not always apply to employee share options, EIS/VCT situations, or specific reorganizations. For your exact case, check the detailed HMRC guidance.