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Frequently asked questions
Which tax year does this cover?
The 2025/26 tax year, 6 April 2025 to 5 April 2026, with a filing deadline of 31 January 2027. The Annual Exempt Amount is £3,000, and gains are taxed at 18% within your remaining basic-rate band (up to £50,270 of income) and 24% above it.
Is my financial data uploaded anywhere?
No. Your files are read and processed in your browser. They are not sent to a server. Closing the tab clears them.
Which HMRC rules does it use?
All three share-matching rules, in order: same-day first, then shares bought back within 30 days, then the Section 104 pool (reference CG51560).
Should I upload more than one year of history?
Yes. Upload as much history as you have. The calculator reads every file in date order to build your Section 104 pool, then calculates the 2025/26 disposals. If the same trade appears in two files, it is counted once.
How are dealing fees and stamp duty treated?
The cash amounts from your statement already include fees and stamp duty. Buying costs are added to your cost and selling costs are deducted from your proceeds. Nothing is added on top.
My broker isn't listed. Can I still use it?
Yes. Upload the CSV and choose Set up columns. You map your file's columns to date, asset, buy/sell, quantity and amount, and the calculator reads it.
Is this tax advice?
No. It is a calculator. It does not provide tax advice and does not file your return. Check the figures with a qualified accountant before you file.