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Validation checks

30 automated checks run on your return before you file - what they are, and how to fix the ones that fail.

? What does AprilTax check before I file?
All 30 checks, grouped - HSN, tax arithmetic, documents, e-commerce, reconciliation.
? A validation check failed - what happens now?
Critical vs advisory findings, and the fix → re-run loop.
? Why am I asked to set my turnover slab?
The ₹5 Cr slab decides your HSN rules - filing can't proceed without it.
? A check says my HSN code is "not in the GST master list" - how do I fix it?
The portal rejects unknown HSN codes - correct them in the Review HSN modal.
? Table 12 doesn't match my sales totals - what do I do?
HSN summary vs Tables 4-11 mismatch - usually fixed by regenerating.
? A marketplace row shows negative sales or the wrong tax sign - is that a problem?
Negative net supply is usually fine; an opposite-sign tax needs a fix.
? A check flags "gaps in my invoice series" - should I worry?
Usually cancelled or unused numbers - advisory only, filing isn't blocked.
? "HSN code must be present on every B2B invoice line" - how do I fix it?
B2B lines always need an HSN of at least 4 digits - fill them in the HSN review table.
? My turnover is over ₹5 Cr - what extra HSN checks apply?
6-digit codes everywhere, B2C included, and both HSN sections in the JSON.
? "TCS statement differs from uploaded sales" - what do I do?
The portal's TCS statement and your files disagree - review it in the TCS Match step.
? "TCS statement operators appear in Table 14" flagged an operator - why?
An operator on your TCS statement is missing from Table 14, or listed under the wrong GSTIN.
? "GSTIN format invalid" - my own, or a buyer's. How do I fix each?
A GSTIN that isn't 15 valid characters gets rejected at the portal - here's both fixes.
? Other validation flags, decoded - quick reference
The occasional checks: cancellation rate, GST over 40%, duplicate operators, POS mismatch.
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