CGT Bed-and-Breakfast 30-Day Calculator 2026/27
UK CGT Section 104 share pool + 30-day matching calculator 2026/27 - worked examples with same-day, 30-day, and pool matching for shares + crypto.
Sections 105 (same-day) + 106A (30-day) + 104 (pool) of TCGA 1992 matching rules worked through scenarios. Anti-bed-and-breakfast plus legitimate alternatives bed-and-spouse + bed-and-ISA.
Worked matching scenarios
| Scenario | Pool gain | 30-day match gain | Total gain | Note |
|---|---|---|---|---|
| Sell 500 at £5, buy 200 next day at £5.20 | £300 | -£40 | £260 | Mix of pool + 30-day rule match |
| Bed-and-spouse: holder sells, spouse buys | £1,000 | £0 | £1,000 | 30-day rule does not apply across taxpayers - clean disposal |
| Bed-and-ISA same day swap | £0 | £0 | £0 | 30-day rule matches buy in ISA - blocks tax-loss harvest BUT ISA tax-free thereafter |
Frequently asked questions
What is Section 104 pool?
Pooled holding of same security with weighted average cost. Each new purchase added at cost, each sale withdrawn at average cost.
In what order do the same-day, 30-day and pool rules match a disposal?
Match in order: (1) same-day, (2) 30-day, (3) pool. Each layer used first before next.
Is bed-and-spouse a legal alternative to bed and breakfasting?
Sell to spouse-as-buyer. 30-day rule does not apply across taxpayers. Spouse buys at market price. Gain crystallises for original holder.
How does bed-and-ISA work?
Sell GIA + buy Individual Savings Account (ISA) same day. 30-day rule applies (same person) so original gain crystallisation deferred. But ISA tax-free thereafter.
Applies to crypto?
YES. HMRC applies Section 105 to crypto. Same matching hierarchy. Per-coin pool.