VTR Tax · United Kingdom · The rules
Same day first. Then the next 30 days. Then the pool.
UK rules don't let you choose which coins you sold. They are matched in a fixed order, and the order changes the answer — so we follow it exactly.
Anything bought on the day of the sale is matched first. Then anything bought in the 30 days after it. Only what's left draws from your Section 104 pool — the running average of everything you held before. Day 31 does not match, and same-day buys are reserved before the 30-day rule can claim them.
The order, step by step
One disposal, three rules.
Disposal · 1.00 BTC
Illustrative
- 01
Same-day rule
TCGA 1992 s.105
matched 0.40
remaining 0.60
Acquisitions made on the same calendar day as the disposal, matched at their own cost.
- 02
30-day rule
TCGA 1992 s.106A
matched 0.25
remaining 0.35
Acquisitions in the 30 days after the disposal, oldest first. Known as bed and breakfasting.
- 03
Section 104 pool
TCGA 1992 s.104
matched 0.35
remaining 0.00
Everything remaining, at the pooled average cost of that asset across your whole history.
Fully matched
1.00 BTC · £33,350 allowable cost
Try it yourself
Same trades. Different bill.
One BTC held for years, one bought on the morning of the sale, then one sold. UK rules match the morning purchase. Averaging everything together pulls the cost out of the long-term pool instead, and the gain changes.
Move the sale price. The gap doesn't close, because the mistake is in the cost basis rather than the market.
You hold 1 BTC bought years ago for £10,000.00. On the day you sell, you buy another 1 BTC for £38,000.00. Then you sell 1 BTC.
| Method | Allowable cost | Gain |
|---|---|---|
| Same-day rule (correct)Matches the morning's purchase at its own cost | £38,000.00 | £2,000.00 |
| Pooled average (naive)Averages both holdings, ignoring the same-day rule | £24,000.00 | £16,000.00 |
£14,000.00 over-reported — at every price. The gap is the difference in allowable cost, so moving the market never closes it.
This is the part we do for you.
You should not have to run this by hand across a year of trading. Connect Kraken and every disposal comes out matched, with the working attached.