UK Tax Lab · 2024/25 rates

HMRC, but interactive.

CGT bands, the 30-day rule, S104 pooling, dividend tax, ISA vs GIA, stamp duty. Move the sliders, add trades to the timeline, watch the tax move.

Educational only — not tax advice. Rates: England & Wales, 2024/25 tax year.

Capital Gains Tax

CGT — the £3,000 cliff

Every disposal above your is taxed. Your income band decides whether it’s .

Annual income (salary etc.)£45,000

Capital gain in the tax year£15,000

Income band: basic · personal allowance: £12,570. Basic-rate room for CGT: £5,270.

Gross gain

£15,000

Annual allowance

− £3,000

Taxable at 18%

£5,270

Taxable at 24%

£6,730

CGT due

£2,564

Effective rate

17.1%

The gain sits on top of your income. Any part that fits in the remaining is 18%; the rest is 24%. The is deducted first. Rates shown are for disposals on/after 30 Oct 2024; earlier disposals in 2024/25 used 10% / 20%. Personal allowance is tapered above £100k income and fully gone at £125,140, which pushes more of any gain into the 24% band.

Share matching

Same-day, 30-day, S104 pool

Build a mini trade history. HMRC matches sells to buys in a fixed order — this is what stops you from .

Scenarios:

Save current as:Stored in this browser. Same name overwrites. Cleared by the global Reset.

Each row is one trade in your history. Pick Buy or Sell, set the day it happened (day 1 = start), how many shares, and the price per share (£). HMRC then matches every sell against your buys in a fixed order — the log on the right shows what got matched to what.

Trades

SideDay #SharesPrice / share

£

TimelineHover a trade row to highlight it

d0

d30

d60

d90

d120

Buy Sell30-day window after sell (bed & breakfast trap)Dot size ∝ share qty

Total gain

£0

Pool at end

100 sh

Matching logeach event = one trade

Same-day 30-day S104 pool Unmatched

d1BUY100 sh @ £10.00
+ 100 sh into pool
Pool:
S104 · 100 shavg £10.00 · total £1,000
d100SELL100 sh @ £5.00
+£0 gain
Matched against
100
- 30-DAY100 sh @ £5.00← buy d110
Proceeds
£500
Cost basis
£500
Gain
£0
Pool after:
S104 · 0 shavg — · total £500
− 100 sh
d110BUY100 sh @ £5.00
+ 100 sh into pool
Pool:
S104 · 100 shavg £10.00 · total £1,000

HMRC matches sells in this order: , then any buy in the (blocks “bed & breakfasting” a loss), then the at average cost.

Dividends

Dividend tax — three rates on top

Dividends sit above your salary in the income stack. First , then .

Other income£45,000

Dividends received£3,000

Start band: basic. First are always tax-free.

Dividends

£3,000

Allowance

− £500

@ 8.75%

£2,500

@ 33.75%

£0

@ 39.35%

£0

Tax due

£219

Net dividends kept

£2,781

Wrappers

ISA vs GIA over time

Compound growth minus the tax drag of dividends and CGT on exit. The gap is the value of the .

Monthly contribution£500

Years20

Annual growth7%

Dividend yield2%

Your other income£45,000

Note: ISA subscriptions capped at £20,000/yr — shown values assume you stay within it.

ISA (tax-free)GIA (net of div & CGT drag)

Total invested

£120,000

ISA final

£255,203

GIA (pre-CGT)

£249,810

CGT on exit

£22,826

GIA after CGT

£226,984

ISA advantage

£28,219

Transaction cost

Stamp duty (SDRT)

A you pay every time you buy UK-incorporated shares. AIM, ETFs and foreign shares are exempt.

Purchase amount£10,000

Market

Purchase

£10,000

Rate

0.50%

Stamp duty

£50

Total cost

£10,050

is charged on buys of UK-incorporated shares settled in CREST. , most ETFs, gilts, and foreign shares are exempt. Above £1,000 paper transfers pay instead (rounded up to nearest £5).

Reference

Wrapper cheatsheet

How each account is taxed inside and on exit.

Wrapper	Contribution limit	CGT	Dividends	On exit
ISA	£20,000/yr	None	None	Tax-free
SIPP (pension)	£60,000/yr*	None inside	None inside	25% tax-free, rest = income tax
GIA	Unlimited	18% / 24%	8.75 / 33.75 / 39.35%	Taxed as you go
Spread bet	N/A	None (gambling)	N/A	Losses not deductible either
CFD	N/A	18% / 24%	N/A (PILs)	Losses offsettable

*SIPP: , tapered for high earners; capped at relevant UK earnings.