Bed and Breakfast CGT Calculator (30-Day Rule)
Calculate capital gains tax implications of the bed and breakfast share matching rules. Model the 30-day same-day and next 30-day rules and plan tax-loss crystallisation.
B&B Share Matching — CGT Calculator
The 30-day 'bed and breakfast' anti-avoidance rule prevents you from selling shares at a loss and buying them back within 30 days to crystallise a CGT loss. Disposals are matched against: (1) Same-day acquisitions, (2) Acquisitions in next 30 days, (3) Section 104 pool.
Shares Repurchased Within 30 Days (B&B Rule)
Average cost of shares in your Section 104 pool
Frequently Asked Questions
What is the 'bed and breakfast' CGT rule?
The 'bed and breakfast' rule (TCGA 1992 s.105) prevents investors from selling shares to crystallise a CGT loss and then immediately buying them back to reset the cost base. If you sell and repurchase the same shares within 30 days, the disposal is matched to the repurchase price rather than the pool average.
What is the share identification order for CGT?
For UK individuals, disposals of shares are matched in this order: (1) Same-day acquisitions, (2) Acquisitions in the next 30 days (bed and breakfast), (3) Section 104 pool (using average cost). This order applies per company and per share class.
Does the 30-day rule apply to bed and ISA?
No. Transferring shares into a stocks and shares ISA is a CGT disposal but acquiring the same shares within the ISA does not trigger the B&B rule — because the ISA acquisition is treated as a different asset class for matching purposes. This is known as 'bed and ISA'.
How can I still crystallise a CGT loss?
Options include: Bed and ISA (sell, wait 30+ days OR move into ISA), Bed and Spouse (sell, spouse buys same shares — note: spouses are independent taxpayers), or simply wait 30 days before repurchasing. Index-tracking alternatives can achieve economic re-exposure immediately.
Does the 30-day rule apply to funds and ETFs?
Yes. The same share identification rules apply to units in unit trusts, shares in OEICs, and ETF shares. If you sell a fund and buy it back within 30 days, the B&B rule applies. However, switching to a nearly-identical fund (e.g., same index, different provider) does not trigger the rule.
What is a Section 104 pool?
The Section 104 pool (S104 pool) is the average cost pool for shares of the same class in the same company that you've acquired over time. When you sell shares not matched by same-day or 30-day rules, the gain is calculated using the average pool cost per share.
Does the bed and breakfast rule apply to ISA investments?
The B&B rule applies to the sale of shares outside the ISA. If you sell shares outside the ISA and repurchase the same shares within 30 days (whether inside or outside the ISA), the B&B rule applies to the outside-ISA disposal.
What records do I need to keep for share matching?
You must keep records of: date and price of every share acquisition (including dividends reinvested), date and price of every disposal, any corporate actions (splits, consolidations, rights issues), and S104 pool running balance. HMRC can request these records up to 6 years after the relevant tax year.