Capital gains tax (CGT)

Also called: capital gains, bed and isa, 30 day rule, section 104

Tax on the profit when you sell shares outside an ISA or pension.

Formula

Taxable gain = Sale proceeds − Cost (incl. fees) − £3,000 annual allowance

Worked example

1. Bought for £5,000, sold for £9,500: gain £4,500
2. Minus £3,000 allowance = £1,500 taxable
3. Basic rate 18% → £270; higher rate 24% → £360

How to read it

Shares in an ISA are free of capital gains tax. Using the allowance each year (for example with a Bed & ISA) can save a lot over time. HMRC has special rules for which shares count as sold: same day, then the next 30 days, then the average cost pool.

See it with real numbers: Capital gains → (free account)