A GST tax invoice is a legal document. Most mistakes we see are not about tax rates; they are missing fields and wrong states. Here is the checklist we built Accounting around.
On every invoice
- Your GSTIN, legal name and address — as registered, not the trade name alone.
- A unique, sequential number for the financial year. Gaps and reuse are what auditors look for first.
- Date of issue.
- The customer's name, address and GSTIN if they are registered. For a B2C sale above ₹50,000 to another state, the name and address are required even without a GSTIN.
- Place of supply. This decides whether the invoice carries CGST + SGST (same state) or IGST (another state). The most common error in small businesses is a customer's billing state left blank.
- HSN or SAC code per line, at the digit count your turnover requires.
- Taxable value, rate and tax amount per line, and the totals.
- Whether tax is payable on reverse charge.
- Signature — a digital or printed signature of the supplier or an authorised person.
Also, depending on you
- E-invoice IRN and QR if your turnover crosses the e-invoicing threshold for B2B invoices.
- E-way bill for goods moved above the value limit.
What software should do
Number the invoices, pick the tax split from the customer's state, carry HSN and rates from the item master, generate the IRN and e-way bill, and post the whole thing to the books. If you are typing tax amounts, the software is not doing its job.
This is general information, not tax advice. Your CA knows your registration and your thresholds.