GST for small business: when to register, returns & common mistakes

GST feels heavy at first, but for most small businesses it comes down to three questions: do I need to register, which returns do I file, and how do I avoid the errors that trigger notices?

When registration is needed

Registration is generally driven by turnover thresholds and the type of supply (goods vs services, and whether you sell across states or online). If you sell on e-commerce platforms or interstate, registration is often required regardless of turnover.

Which returns you file

Most regular taxpayers file outward-supply and summary returns periodically, plus an annual return above certain turnover. The Composition scheme reduces filing frequency for eligible small businesses but limits input credit.

Common mistakes that cause notices

• Mismatch between your returns and the auto-populated data.
• Claiming input credit without valid supplier invoices.
• Late filing — interest and late fees add up quickly.
• Wrong tax rate or HSN/SAC classification.

Do the maths first

Use the GST calculator to check inclusive vs exclusive amounts before you quote a price or raise an invoice, then keep supplier invoices clean so input credit is not lost.