Catch up on two years of overdue Dutch taxes

Claude Code helped a person almost two years behind on taxes untangle expenses, look up receipts and invoices, and navigate the Dutch tax system.

What They Did

They built a local Python-based accounting workflow with Claude Code for a Dutch B.V. with a holding structure. Claude wrote scripts to pull two years of transactions from the Revolut API and bank CSVs, scrape Gmail for receipts and invoices, categorize 330+ transactions with LLM judgment, calculate VAT and reporting totals, and flag 19 edge cases for the accountant instead of deciding them alone.

How It Went

In one afternoon it produced reports in the Dutch tax agency’s box format, cut the accountant’s workload from about 20 hours a year to 5, and caught that the shareholder-loan threshold had been exceeded by EUR 11K. The person still kept the accountant for corporate tax, R&D credits, and annual accounts.

Worth Knowing

During runtime it ran locally with external calls only to the bank and Gmail for source data; the API was mainly used earlier while Claude wrote and debugged the code.