When the IRP rejects an invoice, the error code is rarely the whole story. Complifly groups rejections into five classes so the resolving action is obvious.
1. Schema validation
Structural problems — a missing mandatory field, a malformed GSTIN, an HSN that fails the checksum. These are caught by the mapping engine before submission whenever possible.
2. Value mismatch
Tax computed by the ERP disagrees with NIC's recomputation. The audit layer records both values so reconciliation is a diff, not an investigation.
3. Duplicate document
The document hash already produced an IRN. Complifly suppresses the duplicate and returns the original IRN rather than erroring.
4. Authorisation / session
GSP token or session issues. These retry deterministically with backoff and never double-submit.
5. Policy / eligibility
The taxpayer or document is not eligible (e.g. e-invoicing threshold). Surfaced as an alert, linked to the relevant knowledge article.
