File a German tax return from bank statement PDFs by talking it through with Claude

Posted

Oct 13, 2026 by Cristian Măgherușan-Stanciu (@magheru_san)

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Last checked

Oct 21, 2026

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Method:

How we verify

Evidence: Described by posterThe person describes what happened in words, without screenshots or video.

Outcome

Cristian Măgherușan-Stanciu, a freelancer, had put off a 2025 German tax return for months. Using the Open Computer Use MCP connector, Claude browsed the bank site, downloaded every monthly ING DiBa statement PDF, wrote small scripts to pull the transactions into a CSV, sorted them by purpose (spotting cloud and software business expenses and asking about a few unclear ones), and filled in and submitted the SteuerGo form after a careful review. To check it, Măgherușan-Stanciu had Claude redo previous years: the numbers came within a few euros of what had been filed, the gap coming from monthly exchange rates Claude looked up. It took about 6h of conversation over a couple of days.

AI tool

Claude

The source didn't share its exact prompt, so we wrote this from what it describes.

What the prompt labels mean

Before you start, ask me 1–3 short questions about anything important that's missing below. Keep them quick. Then do the task, checking in with me at the key points.

Goal: Prepare my annual tax return from my bank statements, with business and personal spending sorted out.

What I can give you (ask for whatever's missing):
- Country, tax year and the filing service I use: [DETAILS]
- Bank statements for the year (PDF or CSV): [ATTACH]
- Employed, freelance or both, and my usual business expenses: [DETAILS]

You're not my accountant or financial adviser. Show your working, label estimates as estimates, and tell me which points a professional or the official source should confirm.

Rules:
- Extract every transaction into one table and categorize it; list the ones you're unsure about and ask me instead of guessing.
- Keep business and personal spending separate, and note which rule each deduction relies on.
- For foreign-currency items, say which exchange rate you used and where it came from.
- Before anything is submitted, show me the filled form field by field for review.
- If a site asks me to sign in, pause and let me do it myself (including any CAPTCHA or two-step code); never guess or store passwords.
- Ask for my OK before you pay, book, send, submit or cancel anything.
- Check facts that can change (prices, opening hours, dates, availability, rules) against the official source, and tell me anything you couldn't verify.

Output: The categorized transaction table, a summary of the figures for each form section, and the filled form ready for my review.

You'll know it worked when: the return is filed, and spot-checks against my own records match.

Before you start, ask me 1–3 short questions about anything important that's missing below. Keep them quick. Then do the task, checking in with me at the key points.

Goal: Prepare my annual tax return from my bank statements, with business and personal spending sorted out.

What I can give you (ask for whatever's missing):
- Country, tax year and the filing service I use: [DETAILS]
- Bank statements for the year (PDF or CSV): [ATTACH]
- Employed, freelance or both, and my usual business expenses: [DETAILS]

You're not my accountant or financial adviser. Show your working, label estimates as estimates, and tell me which points a professional or the official source should confirm.

Rules:
- Extract every transaction into one table and categorize it; list the ones you're unsure about and ask me instead of guessing.
- Keep business and personal spending separate, and note which rule each deduction relies on.
- For foreign-currency items, say which exchange rate you used and where it came from.
- Before anything is submitted, show me the filled form field by field for review.
- If a site asks me to sign in, pause and let me do it myself (including any CAPTCHA or two-step code); never guess or store passwords.
- Ask for my OK before you pay, book, send, submit or cancel anything.
- Check facts that can change (prices, opening hours, dates, availability, rules) against the official source, and tell me anything you couldn't verify.

Output: The categorized transaction table, a summary of the figures for each form section, and the filled form ready for my review.

You'll know it worked when: the return is filed, and spot-checks against my own records match.

Before you start, ask me 1–3 short questions about anything important that's missing below. Keep them quick. Then do the task, checking in with me at the key points.

Goal: Prepare my annual tax return from my bank statements, with business and personal spending sorted out.

What I can give you (ask for whatever's missing):
- Country, tax year and the filing service I use: [DETAILS]
- Bank statements for the year (PDF or CSV): [ATTACH]
- Employed, freelance or both, and my usual business expenses: [DETAILS]

You're not my accountant or financial adviser. Show your working, label estimates as estimates, and tell me which points a professional or the official source should confirm.

Rules:
- Extract every transaction into one table and categorize it; list the ones you're unsure about and ask me instead of guessing.
- Keep business and personal spending separate, and note which rule each deduction relies on.
- For foreign-currency items, say which exchange rate you used and where it came from.
- Before anything is submitted, show me the filled form field by field for review.
- If a site asks me to sign in, pause and let me do it myself (including any CAPTCHA or two-step code); never guess or store passwords.
- Ask for my OK before you pay, book, send, submit or cancel anything.
- Check facts that can change (prices, opening hours, dates, availability, rules) against the official source, and tell me anything you couldn't verify.
- Rerun the same method on a year I've already filed and show me how close it gets, as a check.

Output: The categorized transaction table, a summary of the figures for each form section, and the filled form ready for my review.

You'll know it worked when: the return is filed, and spot-checks against my own records match.

Before you finish: re-read my goal and constraints, check your answer against each one, and list anything you assumed or couldn't confirm.

Source

https://x.com/magheru_san/status/2109963791853043858