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GST for Small Businesses (2025): Filing Calendar & ITC Checklist

Author: SmartCalcs Expert Team
Reviewed by: Chartered Accountant (India)
Last updated: November 4, 2025

Simple, step-by-step GST compliance for small businesses: filing dates, invoice rules, ITC reconciliation, and how to avoid penalties.

Who Should Use This Guide

Small businesses registered under GST (composition/regular), freelancers, agencies, retail shops, and service providers who need a quick, practical compliance checklist.

Monthly vs Quarterly Filing (At a Glance)

Monthly Filers

  • GSTR‑1: 11th of next month
  • GSTR‑3B: 20th of next month
  • Pay tax + reconcile ITC monthly

Quarterly Filers

  • GSTR‑1: Last of next month
  • GSTR‑3B: 22nd of next month
  • Reconcile ITC every month, file quarterly

Small Business GST Checklist (Every Month)

  1. Download GSTR‑2B/2A and match with purchase register
  2. Follow up with vendors for missing invoices/HSN or wrong GSTIN
  3. Verify place of supply and tax type (CGST+SGST vs IGST)
  4. Raise compliant sales invoices with HSN/SAC, tax breakup, and place of supply
  5. Compute net GST (Output – Eligible ITC) and pay on time
  6. File GSTR‑1, then GSTR‑3B; keep proofs and challans

ITC Reconciliation – Quick Steps

Claim ITC only when:

  • Invoice is in your name with correct GSTIN and HSN/SAC
  • Goods/services received; supplier filed GSTR‑1 and tax reflected in GSTR‑2B
  • Payment to supplier made within 180 days (else reverse with interest)
  • Not a blocked credit (personal use, motor vehicles, etc.)

Common Mistakes to Avoid

  • Wrong place of supply causing IGST/CGST/SGST mismatch
  • Missing mandatory fields on invoices (HSN/SAC, tax rate, place of supply)
  • Not reconciling GSTR‑2B with purchases monthly
  • Late filing leading to fees/interest and ITC issues for customers

Handy Tools

References