My Factory BillsGST invoice format: what every tax invoice must contain
A tax invoice under GST is a prescribed document, not just a bill. If a required field is missing, your buyer can have trouble claiming input tax credit — which is usually how you find out, in the form of an annoyed customer at the end of the month. Here is what has to be on it.
The required fields
- The words "Tax Invoice" and your firm's name, address and GSTIN.
- A serial number, unique within the financial year, from a continuous series.
- Date of issue.
- Buyer's name, address and GSTIN, where the buyer is registered.
- For unregistered buyers above the prescribed value, the buyer's name and address, and the address of delivery with its state and state code.
- Description of goods or services, with the HSN or SAC code.
- Quantity and unit for goods.
- Total value, taxable value after any discount, and the rate and amount of tax broken into CGST, SGST/UTGST, IGST and cess as applicable.
- Place of supply with the state name — this is what decides which taxes apply.
- Whether tax is payable on reverse charge.
- Signature or digital signature of the supplier or an authorised person.
The exact thresholds for HSN digits and for unregistered-buyer details depend on your turnover and change from time to time. Your CA will tell you which apply to you this year.
CGST + SGST, or IGST?
This is the single most common error, and it comes down to one comparison: your place of supply versus your own state.
- Same state — charge CGST and SGST, each at half the total rate. An 18% item becomes 9% CGST plus 9% SGST.
- Different state — charge IGST at the full rate. The same 18% item is 18% IGST.
Getting this wrong is not a rounding problem. The buyer cannot properly claim credit for the wrong tax head, and correcting it means amending a filed return. If you bill across state lines at all, this is the field to double-check — or to have software decide from the buyer's state so it is never a judgement call.
Invoice numbering: boring, and worth getting right
The series must be continuous and unique within the financial year. In practice that means:
- No gaps. A missing number invites the question of what was in it. If a bill is cancelled, keep the number and mark it cancelled rather than deleting it.
- No duplicates. Two documents with one number is the classic symptom of an invoice book being written in two places at once, or a spreadsheet copied.
- Restart cleanly each financial year, keeping any prefix consistent.
- One series per firm. If you run two firms, they each need their own.
Tax invoice, bill of supply, or something else
| Document | When you issue it |
|---|---|
| Tax invoice | Normal taxable supply by a registered person |
| Bill of supply | Exempt supplies, or if you are under the composition scheme — no tax shown |
| Credit note | Value or tax reduces after the invoice — returns, discounts, corrections |
| Debit note | Value or tax increases after the invoice |
| Delivery challan | Goods move without a sale — job work, samples, transfers |
Five mistakes that cause mismatches at filing time
- A wrong or missing buyer GSTIN. One mistyped character and the invoice does not reach the buyer's credit statement.
- The CGST/SGST vs IGST mix-up described above.
- Discount applied after tax instead of before. Tax is computed on the value after any discount recorded on the invoice.
- An HSN code that does not match the item. Copying a line from an old bill for a different product is how this happens.
- Rounding each line separately so the total does not tie to the sum of its parts.
Every one of these is a data-entry error rather than a knowledge gap — which is exactly the kind of error software should be preventing rather than you catching.
A format you can copy
Lay the document out in this order and you will have covered the required fields:
Header — "Tax Invoice" · your firm name, address, GSTIN · invoice number and date
Parties — bill-to name, address, GSTIN · ship-to address · place of supply with state and code
Line items — description · HSN · quantity and unit · rate · taxable value
Tax — CGST, SGST or IGST shown separately with rate and amount · cess if any
Totals — invoice total in figures and in words · reverse charge yes/no
Footer — bank details if you want payment by transfer · signature
Or stop formatting invoices altogether
Every field above is a field My Factory Bills fills for you. Pick the party and the items; the app carries the HSN codes, decides CGST+SGST versus IGST from the buyer's state, keeps the number series continuous, prints the amount in words, and produces the PDF. At month end the same entries become your sales register and GSTR-1 and GSTR-3B summaries, so filing is reading numbers rather than rebuilding them.
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