Interactive Brokers (IBKR)¶

cgt-calc reads the CSV downloaded from the Transaction History page in the Interactive Brokers Client Portal. It does not read Activity Statements, Flex Queries, PDFs or Excel files.

Use an account whose base currency is GBP. The importer checks the base currency in the CSV and rejects other currencies. Include taxable accounts only; activity inside an ISA is outside the capital gains calculation.

Export the transaction history¶

Export the complete history rather than only the tax year. Earlier acquisitions can still affect disposals in the year being calculated, and the cash deposits at the start of the account help the balance check detect an incomplete export.

1. Sign in to the Interactive Brokers Client Portal in a web browser.
2. Open Performance & Reports → Transaction History. Alternatively, open Menu → Reporting → Transaction History.
3. Select Custom as the period and set the start to the account's first transaction. Set the end to today, or at least 30 days after the end of the tax year you are calculating.
4. Clear any transaction-type or symbol filters so the export includes trades, income, fees and cash movements.
5. Download the table using its CSV export control.

IBKR's current Transaction History instructions show the menu path, period selector, column configuration and filters.

Keep the downloaded CSV unchanged. The filename does not matter.

Do not substitute an Activity Statement or a Flex Query CSV: their sections and headings are different even though they are also available from Performance & Reports.

You can compare the file's structure with the synthetic example CSV.

Generate the report¶

For the 2025/26 tax year, run:

cgt-calc --year 2025 --interactive-brokers-file U12345678.TRANSACTIONS.20240101.20260505.csv

--year 2025 means 6 April 2025 to 5 April 2026. Follow Generate and Review a Report to find and check the output.

The Transaction History export contains cash deposits and withdrawals, so a complete export should normally pass the balance check. Do not add --no-balance-check simply to bypass an error; first check the date range and filters as described in Troubleshooting.

Supported activity¶

The importer recognises these literal values from the CSV's Transaction Type column:

For a GBP-base account, IBKR reports gross amounts, commissions and net amounts in GBP, so every row is recorded in GBP whatever the security is priced in. Price Currency describes the unit price alone: when the CSV also supplies an Exchange Rate, cgt-calc converts a foreign-currency unit price to GBP before calculating the acquisition or disposal.

cgt-calc does not treat a currency conversion as a disposal. It applies the Forex Trade Component Net Amount to the cash balance and reports no gain or loss on the conversion itself.

An Other Fee only changes the tracked cash balance, whether it names a security, as an ADR fee does, or none, as a market-data subscription does. cgt-calc does not add it to the allowable cost of any holding. An ADR fee is a charge for holding the shares and a subscription a charge for running the account, and HMRC treats a fee as an incidental cost you can deduct only where it was paid for a purchase or a sale.

cgt-calc does not work out what an Other Fee was paid for. IBKR's reporting reference lists a corporate action election fee among its other fees too, and a fee like that may have been paid for a purchase or a sale. If one of yours was, the gain cgt-calc reports on those shares is too high by that fee. To have it deducted, delete the Other Fee row from a working copy of the export and add its amount to both the Commission and the Net Amount of the trade it was paid for: a -5.00 fee on a sale turns a Commission of -3.00 into -8.00 and a Net Amount of 597.00 into 592.00.

IBKR descriptions for dividends and payments in lieu can put an ISIN in parentheses immediately after the symbol. cgt-calc uses that identifier when deciding whether a supported double-taxation treaty applies.

Rows with no symbol¶

IBKR writes - in the Symbol column on a row that names no security. cgt-calc reads that as no symbol, rather than as a holding called -, so one of the types above is handled differently depending on whether a security is named. A Foreign Tax Withholding naming a security is dividend tax. One naming no symbol is tax withheld from your cash interest, so it is reported as interest tax.

Tickers and exchange listings¶

IBKR can report one security under different tickers. cgt-calc combines supported ticker pairs into one holding when it can identify the security by ISIN, from your file or from the bundled list of securities, and reports it under one ticker, which may not be the one you traded: CSPX, for example, is reported as CSP1. An ISIN in a dividend description can also identify trades under that ticker, wherever the dividend appears in your input.

Without an ISIN or reference mapping, tickers can remain separate without an error. If your report shows one security twice, compare the ISINs in its dividend descriptions or IBKR's instrument details. If they match, add all its verified tickers to one row in your ISIN to ticker mapping. Rerun and check that the report shows one holding.

Adding a mapping does not add support for a new ticker pair. If the holding remains split, report both tickers and the ISIN as described in Troubleshooting; do not rely on that holding's calculated gain until resolved. If your input assigns different ISINs to one ticker, cgt-calc stops with an error.

Known limitations¶

• Only the transaction types listed above are mapped. Any other value stops the import with Unknown type; do not delete the row merely to make the calculation run.
• Cash Deposit and Withdrawal rows are supported, but transfers of shares or funds between accounts are not. Corporate actions such as splits, mergers and spin-offs are not mapped from an IBKR export either; record a split or consolidation as a RAW STOCK_SPLIT row stating the change to your whole pooled holding. If the export contains the corporate-action row, it stops the import, so remove it from a working copy only when adding the RAW replacement.
• The importer does not read an asset-class field. It has been validated for ordinary share and fund trades; do not rely on it to calculate options, futures, bonds, contracts for difference or crypto assets.
• The Account column is not used to keep separate ledgers. Rows for multiple taxable IBKR accounts in one CSV are combined under one broker balance and portfolio.

Troubleshooting¶

Unexpected base currency¶

The CSV says that the account's base currency is not GBP. Changing the text in the file would not convert any amounts, so use a GBP-base account export instead.

Price is in ... but the Exchange Rate column is missing or empty¶

A Buy or Sell row prices the trade in a currency other than GBP but gives no rate to convert it with, while its gross amount, commission and net amount are in GBP. The price cannot be checked against the amount, and a guessed rate would put a wrong cost or proceeds in the report, so the import stops. Re-export the statement with the Exchange Rate column filled in for that row — a Buy or Sell always needs a price, so clearing Price and Price Currency only trades this error for a missing-price one. Other row types are unaffected: only a trade's price feeds the calculation, so a dividend, fee or interest row keeps a foreign, unconverted Price Currency rather than being refused over a price nothing reads.

Couldn't find Transaction History header¶

Check that the file came from Performance & Reports → Transaction History and is the CSV export. Activity Statements, Flex Queries and files converted from PDF use different layouts.

CSV header mismatch¶

The Transaction History page lets you configure its columns, while cgt-calc requires the fields it uses and rejects fields it does not recognise. Export the standard table without changing its columns. Price Currency and Exchange Rate are accepted optional columns.

If an unchanged export still fails, first upgrade cgt-calc using the same method you used to install it. If the error remains, open a GitHub issue with:

• your cgt-calc version from cgt-calc --version;
• the complete error message; and
• the CSV header and a sanitised failing row.

Do not upload an unredacted file: the report contains account identifiers, holdings and other sensitive financial information.

Unknown type¶

Compare the named transaction type with Supported activity. The row may represent an unsupported corporate action or position transfer. Do not remove it unless you replace it with an equivalent supported transaction whose UK tax treatment you have verified.

Reached a negative balance¶

Re-export the history from the account's first transaction and make sure no transaction-type or symbol filter is active. A shortened or filtered export can omit the deposit, sale or dividend that funded a later transaction.

Use --no-balance-check only if you have confirmed why the export cannot reconcile and have checked its completeness another way.