Accounting system setup is the work done before the first live invoice is posted. It includes the chart of accounts, customer and vendor masters with GSTIN and TDS sections, item masters with HSN/SAC and tax rates, bank and cash ledgers, cost centres if the entity needs them, and user access rights. Opening balances are taken from the last audited or last closed trial balance and are tied to a dated statement of affairs.
GST and TDS configurations are tested with sample invoices before go-live so that the first GSTR-1 and the first TDS statement are not the first test of the masters. Number series for invoices, credit notes, and payment vouchers are set to match the statutory and internal numbering the entity will use.
Migration from a previous system or from spreadsheets includes a mapping of old ledgers to new ones and a reconciliation of trial balances on the cut-over date. Differences are posted as identified opening adjustments, not left as a balancing figure in suspense.
A short operating note — who posts sales, who posts payments, who reviews BRS — is part of the setup, because software without a posting routine returns to informal records within a few weeks.