How to connect and compute

Before you start

You need two things: an assistant that speaks MCP, and broker statements on disk.

MCP is the protocol an assistant uses to reach an external tool. Claude Code, Claude Desktop, Cursor and ChatGPT in developer mode all support it. Broker files stay with you — the assistant reads them locally and sends us numbers only.

Connecting

You will find the key in the panel. In Claude Desktop and Cursor you put the same address and the same Authorization: Bearer … header into the configuration file.

The key is your accessWhoever holds the key uses your balance. Do not paste it into a shared chat or a repository. If that happens, exchange the key in the panel — the old one stops working immediately.

Your first calculation

Tell the assistant in your own words, for example:

Compute my PIT-38 for 2026. The XTB and Revolut statements are in Downloads.

The assistant fetches the rules, reads the files and goes through three steps: check, quote, compute. It asks for your consent before drawing anything from the balance.

Send purchases from earlier years tooA sale without its matching purchase has no acquisition cost, so the tax comes out too high. If you sold in 2026 something bought in 2019, the 2019 statement is needed as well.

Commands

Command	What it does	Balance
validate	Checks the contract and scans for personal data. Computes nothing.	free
quote	How many transactions will be charged and what will be left.	free
calculate	The tax, the section breakdown, the corrections.	charges
balance	Balance and expiry date.	free

Checking and quoting are free on purpose: correcting data should not cost money.

Balance and top-ups

You pay per transaction, not per month.
Recomputing the same transactions is free — we recognise them by content, so a different row order or a re-export costs nothing.
A top-up adds to the remaining balance.
An unused balance expires at the end of the tax season.

Refusals and what to do

Code	Meaning and what to do
QUOTA_EXCEEDED	Not enough balance. Nothing was charged. The reply says how many transactions are missing.
PII_DETECTED	Personal data appeared in the payload. We name the field and never repeat the value.
CONTRACT_INVALID	A field has the wrong format. The list is in the reply — the assistant fixes it and sends again.
NO_ACTIVE_BALANCE	There is no purchased package.

Rules for the assistant

The normalisation rules are published at a fixed address, /rulebook/pl/v1 — that is what your assistant reads. You do not need to know them; they are public so that what we send, and why, can be checked.

The address is versioned by jurisdiction, not by interface language: Polish rules stay under /rulebook/pl/ no matter which language you are reading this page in.