"HSN code must be present on every B2B invoice line" - how do I fix it?

1. Unlike B2C, every B2B invoice line must carry an HSN code - at least 4 digits, regardless of your turnover. A related check ("HSN/SAC code is shorter than 4 digits") fires when a code is present but too short.

2. Open Review HSN Code and switch to the B2B tab - every row without a code (or with a too-short one) is flagged red.

3. Type the code, use Find by name to search by product, or accept the engine's suggestion with Use.

4. Regenerate the return and Re-run checks.

💡 Companion check: "HSN B2B section must be included when any B2B data is in the filing" - if it fires, tick the Include hsn_b2b checkbox under the HSN-wise summary before downloading. The portal rejects a return with B2B invoices but no B2B HSN section.