Why the portal rejects an invoice at IRN generation

Every rejection carries a code and a message, and the message names the field at fault more often than people expect, so read both first. Retyping hides the clue.

Keep a rejection log for a fortnight, writing the code, field and cause, because a pattern appears fast and usually points at two or three master records. It is rarely forty separate mistakes.

A GSTIN that fails its check digit is the classic case, and so is a GSTIN whose state code disagrees with the state typed in the address. Typos in the party master cause both.

Item faults are as common. A blank HSN, an HSN with the wrong number of digits for your turnover, or a unit of measure typed as free text will all be refused. The portal expects its own unit codes.

Fix the master, not the invoice. One correction there protects every future invoice, whereas an invoice-level patch leaves the next invoice to that customer failing in exactly the same way.

A duplicate document number inside one financial year is rejected even when the earlier invoice was cancelled, and staff often reuse a number after a failed attempt. They assume a rejected invoice never existed.

Dates cause trouble too. An invoice dated before the previous number in the same series, or outside the financial year of the series, will not pass. Characters the portal does not accept in the number, such as spaces or certain symbols, also fail the check, usually in the document number field.

Control the series in software. Let the system issue every next number and refuse manual edits, because a person typing a number by hand eventually skips one or repeats one.

The portal checks that IGST appears for interstate supplies and CGST with SGST for local ones, using the place of supply and the GSTIN state codes. Line totals, tax amounts and the invoice value must also add up within a small rounding allowance, or the whole document is refused at generation.

Manual tax overrides fail quietly. A clerk who rounds a figure by hand, or applies a discount after tax was computed, can produce totals that no longer reconcile.

Compute tax once, from rules, in one place, and print only the computed figure on the invoice, the e-way bill and the credit note that follows. Never retype a tax amount.

Most of the faults above can be caught on screen if the software tests the GSTIN checksum, makes HSN mandatory and offers units from a list. Locking the series against edits and blocking tax overrides complete the set, removing most rejections before any call reaches the portal and fills the retry queue.

What remains is real: portal downtime, a buyer’s GSTIN cancelled after you last checked, or a rule that changed this week. Keep those in an exception report that someone reads each morning, and start your own fixes with the three most repeated causes in the rejection log.