CGT Bed-and-Breakfast 30-Day Calculator 2026/27
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 Each new purchase added at cost, each sale withdrawn at average cost.
Same-day vs 30-day vs pool order
Match in order: (1) same-day, (2) 30-day, (3) pool. Each layer used first before next.
Bed-and-spouse legal alternative
Sell to spouse-as-buyer. 30-day rule does not apply across taxpayers. Spouse buys at market price. Gain crystallises for original holder.
Bed-and-ISA mechanics
Sell GIA + buy 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.