FAQ
Questions about the tool itself. Tax questions — Vorabpauschale, options, withholding tax, losses — are answered in the tax FAQ.
Is this tax advice?
No. capi.tax prepares your data and does not constitute tax advice. It reads your broker export, converts the amounts to euro, applies the rules of German tax law and gives you a structured summary for your tax return. The figures are a starting point, not a final verdict. For your personal situation, please review the result and talk to a tax advisor (Steuerberater).
Is my data safe?
Yes. Your data never leaves your computer. Everything is calculated in your own browser, so there is no upload and no copy on a server. We have no technical way to see your transactions. Once you close the page, the data is gone.
Can I verify that?
Yes. Open your browser's developer tools, switch to the network tab and process a file: you will see the application and the exchange rates load, but no upload of your data. Or load the page once, disconnect from the internet, and calculate anyway.
Do I need an account?
No. There is no sign-up, no login and no email prompt. You load your file and get your result.
What does it cost?
capi.tax is currently free. It is a private project — feedback is very welcome. There is no subscription, no payment details and no account.
Which brokers are supported?
Interactive Brokers and Tastytrade. Plus every introducing broker on the IBKR platform — LYNX and CapTrader among them: their Activity Statement comes out of the same IBKR system, so you simply pick Interactive Brokers.
Which file do I need?
From Interactive Brokers the Activity Statement as CSV (not Excel, not PDF); from Tastytrade the Transaction History as CSV. Step-by-step guides are under broker export.
Which tax years are supported?
Tax years from 2018 to the current year. Each year automatically uses the rules that applied in that year, so an older return is calculated under the law of its time.
I have several accounts — what now?
Export one file per account. What matters is that a position's history is complete: if you hold the same share in two accounts, the tax office still treats them per custody account.
Why are some trades missing from my totals?
If a position was opened in an earlier year than the file you uploaded — options bought in 2024 that expire in 2025, say — the closing trade has no matching purchase and cannot be calculated. capi.tax does not guess: it lists such trades as unmatched in the audit-trail tab and leaves them out of the totals. Export a period reaching back to the opening, or add the opening trade in the adjustments tab.
What do the warnings after processing mean?
They show where capi.tax could not confidently classify something — an unknown row type, a missing purchase, a currency trade. None of it is passed over silently: better a visible warning than a quiet assumption inside a tax figure.
My file is not recognised
Check three things: is it really CSV (not .xls or PDF)? Is it from the broker you selected? And does the export contain all sections — for IBKR that means trades, dividends, interest and fees? An export trimmed to a few sections produces incomplete totals.
The file is very large
That is normal for a full year's export. Since everything runs locally, the time depends on your machine. If a yearly export is too large, split it by quarter and load the parts one after another.
Can I save the result?
Nothing is stored on purpose — close the tab and it is gone. So export your report before you leave the page, as Excel, PDF or CSV.
Can I try it without using my own data?
Yes. "Test sample file" shows you a complete result built from sample data, with nothing to upload.
I found a mistake
Get in touch through the contact form. A description of the trade that looks wrong helps — please without attaching your broker file or personal data.
capi.tax prepares your data and is not tax advice. Please review the figures and ask a tax advisor (Steuerberater) about your personal situation.