Capital Gains Tax
from a Trading 212
export

In the Trading 212 app or web platform, open your account History and export it as CSV, covering the whole tax year — 6 April to 5 April, not the calendar year. Include every transaction type; the dividends and deposits are not chargeable but their presence lets the import prove it accounted for every line of your statement.

The export you want lists what you bought and sold. If a platform offers you a "realised gains" or "CGT" report, that is a different document and it is the wrong one — see step 4.

If you have used more than one broker, export from all of them. This matters more than anything else on this page, and step 5 explains why.

A Trading 212 history export carries, per row: the action (Market buy, Market sell, Dividend (Ordinary) and so on), a timestamp, the ISIN and ticker, the number of shares, the price per share with its currency, an exchange rate, and the total in your account currency.

Three things in there routinely go wrong when people do this by hand:

• Fractional shares. Trading 212 sells them, and quantities like 0.4831726 must not be rounded at any point in the calculation.
• Foreign currency. A US holding is priced in dollars and settled in pounds. The gain is computed in sterling, using the rate on each trade — not one rate for the year.
• Non-trade rows. Dividends, deposits, withdrawals, interest and currency conversions are not disposals. Dividends are income tax, not CGT, and dropping them into a gain calculation inflates it.

This is the part that catches almost everyone.

Like most brokers, Trading 212 shows you a result per position based on the average cost of the shares in that account. It is an honest, useful number, and it is not what HMRC's rules produce. UK Capital Gains Tax requires Section 104 pooling with a strict matching order applied first, and the two can differ by a lot:

• Same-day rule. Shares bought on the day you sold are matched against that sale first, at that day's average cost — before the pool is touched at all.
• 30-day rule. Shares bought in the 30 days after a sale are matched against it next, earliest first. Sell at a loss in December and buy back in January and the loss you thought you banked is not banked.
• Section 104 pool. Only what is left is matched against the pool — and the pool is per security, across everything you hold of it, not per account.

You can see the difference for yourself in about thirty seconds with the Section 104 calculator — enter two buys and a sale and compare it against a simple average.

Several platforms will produce one. Its rows are disposals the broker has already matched, with a cost it pooled from acquisitions that are not in the file — and a broker can only ever see its own account. Fed into a tax calculation as if they were trades, those rows enter the pool a second time, and the pooling they carry was wrong for HMRC's purposes to begin with.

Always start from the transaction history.

Then a Trading 212 export alone cannot give you the right answer, however carefully you work through it.

HMRC pools a security across everything you hold of it. If you own VUSA at Trading 212 and VUSA at Hargreaves Lansdown, that is one Section 104 pool, and its average cost depends on purchases made at both. Computing each account separately produces two plausible numbers that are both wrong — and the error is not small, because it lands on the cost side of every disposal.

The 30-day rule crosses brokers too: sell at one and buy back at another within 30 days and the rule still bites.

Doing this by hand for a year of activity is possible and genuinely unpleasant. Every disposal needs the matching order applied in sequence, the pool restated after each event, sterling conversion per trade, and full precision kept throughout. A spreadsheet can do it; spreadsheets that do it correctly are rare, and the failure is silent.

What you need at the end, for the SA108 listed-securities section, is: the number of disposals, total proceeds, total allowable costs, gains before losses, and losses in the year — plus a record of how each figure was reached, in case anyone ever asks.

GainPool reads a Trading 212 export directly. It is the one broker profile validated against a real export — the file is in the test suite and imports on every build, rather than being written from documentation and hoped over.

It merges every broker you use into one pool per security, applies the three matching rules in HMRC's order, converts foreign trades per trade, excludes ISA and SIPP accounts you tag, and shows the working behind each figure. £12, once.

This guide is general information about how the rules work, not tax advice, and Longstop Software is not affiliated with Trading 212. Platform names are the trade marks of their owners. Export layouts change — if yours does not look like this, the checker will tell you what we actually see in it.