Error: files belong to different GSTINs
Run each GSTIN separately with its own register.
Error: period given twice
You attached the same month's JSON twice. Remove one.
No recon.xlsx in the output
Install openpyxl (pip install openpyxl). recon.csv has the same rows.
Too many probable matches
Run with --exact-only, or lower --tolerance.
Claude does not use the skill
Check it is switched on in Settings → Capabilities → Skills, then name it in your message.
The script says a column is missing
Rename your header to one of the names in README, or say the mapping in your message.
Code execution is off
Skills with scripts need code execution enabled in Claude.ai settings.
FAQ
Does it log in to the GST portal or email my suppliers? No. You download the GSTR-2B JSON yourself, and the supplier messages are drafts in a CSV for you to send.
How does it handle a bill the supplier reported a month late? Attach both months' GSTR-2B. The bill matches in the later month and is marked late, so you know which return the ITC belongs to.
What is a probable match? Same supplier, same tax, and a bill number that ends the same (DC/778 vs 778). Confirm it, then fix the number in your register.
Can I claim ITC from this report? It is matching help for your records, not tax advice. Your CA decides what ITC to claim.