Common GST filing mistakes small businesses make
Most GST filing problems aren't dramatic fraud cases — they're small, repeated errors that quietly cost businesses input tax credit or trigger unnecessary notices. Here are the ones that come up most often.
Mismatched invoice details between GSTR-1 and GSTR-3B
GSTR-1 reports your outward supplies in detail, while GSTR-3B is a summary return with tax payment. When the two don't reconcile — a common result of manual data entry errors — it can flag your filings for scrutiny even when the underlying transactions were correctly reported.
Claiming input tax credit without proper documentation
Input tax credit claimed without a valid supplier invoice, or where the supplier hasn't correctly reported and paid their own GST, can be disallowed even if you paid the invoice in good faith. Reconcile your claimed ITC against your GSTR-2B (auto-generated from supplier filings) before claiming.
Missing the filing deadline, even with nil activity
GST returns are due even in months with zero transactions — a "nil return" still needs to be filed. Missing this, even when there's genuinely nothing to report, results in late fees that accumulate for every day of delay.
Incorrect HSN/SAC codes
Using the wrong classification code affects the applicable tax rate and can misrepresent what you're actually supplying. This is especially common for freelancers new to GST who aren't sure which SAC code matches their specific service category.
Not reconciling export invoices under LUT correctly
Marking export invoices incorrectly, or failing to file the LUT before invoicing exports without IGST, can result in an unexpected tax demand later — the export benefit only applies when the correct process and paperwork are in place from the start.