UK CGT Bed-and-Breakfast 30-Day Rule Complete Guide 2026/27

Bed-and-Breakfasting: historical UK tax-loss harvesting practice - sell shares to crystallise gain / loss for CGT, immediately repurchase next day. Section 106A TCGA 1992 (inserted by FA 1998) introduces the "within 30 days" matching rule to prevent it. If you sell shares + repurchase SAME shares within 30 days, disposal matched against repurchase (not Section 104 pool). Effect: no real disposal recognised for CGT. Gain / loss preserved. Genuine BUT: tax-loss harvesting blocked.

3-tier matching hierarchy under Section 105 TCGA 1992 (same-day) + Section 106A TCGA 1992 (30-day) + Section 104 TCGA 1992 (pool): (1) Same-day matching first: shares sold today matched against shares acquired today. (2) 30-day matching next: shares sold today matched against shares acquired in next 30 days. (3) Section 104 pool: remainder matched against pooled holding (weighted average cost). Pool concept: all holdings of same share treated as single asset with average cost. Each new purchase added to pool, each sale withdrawn at average cost. Worked example: Sept hold 1,000 BP shares at £4 average pool cost. Sell 500 at £5 on Oct 1. Buy 200 at £5.20 on Oct 15. Matching: (1) Same-day Oct 1: 0 purchases. (2) 30-day window: 200 of the 500 sold matched against Oct 15 purchase. Gain = (£5 × 200) - (£5.20 × 200) = -£40 LOSS. (3) Pool: 300 of 500 from pool. Gain = (£5 × 300) - (£4 × 300) = £300. Total reportable gain: £260.

Bed-and-Spouse: sell shares, spouse immediately repurchases. Different person + 30-day rule doesn't apply across taxpayers. Gain crystallised by seller. Spouse acquires at market price. Useful for: (1) Tax-loss harvesting: crystallise losses to offset gains. (2) AEA utilisation: maximise each spouse's £3,000 AEA. (3) Band utilisation: shift gain to lower-band spouse. (4) BADR cap optimisation: shift £1m cap usage. Worked example: holder has £20k gain. Sells half (£10k gain). Spouse buys back same day. Wife (basic-rate) reports £10k gain - £3k AEA = £7k × 18% = £1,260. Holder kept other half. Saves vs single seller higher-rate.

Bed-and-ISA: sell shares from GIA + immediately repurchase in ISA. 30-day rule applies (same person): BUT ISA shielded from future CGT entirely. Effect: (1) Sale + repurchase within 30 days = matched: no immediate gain crystallisation. (2) After 30 days, original gain crystallises against Section 104 pool. (3) ISA holdings tax-free: all future gains tax-free. Strategic timing: (1) Use B&I to migrate holdings to tax-free wrapper. (2) Within £20,000 / year ISA limit. (3) Capital gains within AEA absorbed: above AEA, CGT due. Worked - 500 BP shares at £4 cost, £5 current. AEA available: Sell GIA + buy ISA same day. Section 104 match next-day re-buy. £500 gain absorbed by AEA. Net £0 tax + assets now in ISA permanently tax-free.

Sections 104, 105 + 106A TCGA 1992 apply to CRYPTOCURRENCY too: HMRC's view in cryptoassets manual. Same matching hierarchy: same-day, then 30-day, then Section 104 pool. Per-coin pool: BTC, ETH, etc. each separate pool. Implications: (1) Crypto traders cannot bed-and-breakfast: 30-day repurchase matched. (2) Stablecoin shuffling within 30 days: matching applies. (3) Wash trades across exchanges: same crypto, same person, 30-day window = matched. Strategic considerations: (1) Hold 31+ days between sell + repurchase: clean disposal + new acquisition. (2) Crypto-to-crypto trades: each swap = disposal at market value. (3) DeFi yield + reinvestment: complex matching. (4) Pool calculation per coin: track all purchases + disposals separately. (5) Specialist crypto-tax tools (Koinly, Recap): handle Section 104 + 30-day automatically.

Investor checklist: (1) Track Section 104 pool: all purchases + disposals same security. (2) Avoid accidental 30-day rebuy: blocks tax-loss harvesting. (3) Use Bed-and-Spouse: legal alternative to B&B. (4) Use Bed-and-ISA: shift to tax-free wrapper. (5) AEA timing: split disposals across tax years for £3k × 2 + AEAs. (6) Spouse share transfer pre-sale: utilise both AEAs + bands. (7) BADR / IR claim where eligible: 18% / 14% rates. (8) Capital losses claim: carry forward indefinitely. (9) Crypto pool tracking software: Koinly / Recap / CoinTracker. (10) SA filing for capital gains: over £3k or £50k+ disposal proceeds.