Purchase matching — the credit is only what the supplier declared
Import the month's GSTR-2B from the portal; every line is matched to the bills by GSTIN and invoice number; mismatches are named in words; accept, reject or keep pending each line (IMS) and export the actions; write to the supplier from the row.
Menu → Tax → Purchase matching. Download GSTR-2B for the month from the portal (its JSON) and import it for the registration. Every line is matched to the bills (Payables) by the supplier's GSTIN and the invoice number, within thirty days of the date. The amount must agree within a rupee. What differs is named: *amount differs* (the books and the supplier disagree — the note says by how much), *not in books* (the supplier filed a document nobody recorded), *missing in 2B* (a bill in the books the supplier has not declared — no credit this month). *Match…* joins a line to a bill by hand; *Write to the supplier* sends the question from the row. IMS: a matched line is proposed as *accept*; set *reject* when the supplier's line is wrong and *pending* to wait. Export the actions in the portal's shape and upload them. Nothing is submitted from here. Before GSTR-3B: the credit the books claim (table 4) against what the portal will allow (accepted lines with credit available) — the difference is the number to explain before filing.