mikkelkrogsholm/rentemester

Rentemester is an upcoming bookkeeping system for small Danish businesses: freelancers, consultants, sole traders, and small private limited companies (ApS). The README is written in Danish. The pitch is that an AI agent handles the routine bookkeeping work while a hard rule engine in the core decides whether the result is actually correct under Danish accounting and VAT rules. The authors are deliberate that this is not a chatbot bolted onto an accounting tool. The core enforces double-entry bookkeeping, requires that debit equals credit, stores each receipt with documentation, and refuses to silently edit a posting once it has been booked. Errors are fixed by new offsetting entries rather than by changing history, and every action has to be auditable. Their slogan is roughly: the agent acts, the rules judge, the ledger enforces. A typical month is described this way: you forward receipts to a receipts mailbox, Rentemester imports your bank transactions, the system matches lines like Stripe, OpenAI, Google, or train tickets against the receipts, the clear cases are posted automatically, and the rest end up in a short task list, for example a restaurant receipt missing its purpose or a card payment without a matching receipt. At the end of the VAT period it produces a report and an export package for your accountant. The current code is an early prototype with the core already working: a SQLite ledger, append-only history, an audit hash chain for integrity, a Danish chart of accounts, bank CSV import with foreign currency handling, deterministic invoicing including PDF generation and payment registration, late-payment interest and reminder fees under Danish rules, credit notes, VAT reporting, EU reverse charge, CVR registry lookups with a local cache, and deterministic backup snapshots. A runnable demo lives in examples/agent-demo: it imports a bank CSV and six receipts, posts the clear cases automatically, and leaves the rest in an exception queue. It runs locally with no API keys. The README explicitly says the project is not aimed at large companies, payroll, point-of-sale, or stock-keeping.