Not every sale under GST calls for the same document. Charge GST and issue a document that does not show tax separately, or skip GST on an exempt sale and still issue what looks like a full tax invoice, and you create a mismatch that surfaces later during return filing or an audit. The tax invoice vs bill of supply distinction is simple in principle: one is for taxable supplies, the other for exempt supplies or supplies made under the composition scheme. The practical edge cases, especially for businesses that sell a mix of taxable and exempt items, are where it gets confusing.
What a tax invoice is for
A tax invoice is issued whenever GST is actually charged on a supply. It must show the taxable value, the applicable GST rate, and the tax amount split as CGST+SGST or IGST, along with the other mandatory fields such as GSTIN, HSN/SAC, and place of supply. It is the document a registered buyer relies on to claim input tax credit, so its accuracy matters beyond just your own books.
What a bill of supply is for
A bill of supply is issued when no GST is charged on the transaction, either because the goods or services are exempt from GST, or because the supplier is registered under the composition scheme (which does not permit charging GST separately to customers). It carries most of the same identifying details, invoice number, date, supplier and buyer information, description of goods or services, and value, but it does not show a tax rate or tax amount, because none is being collected.
Who typically issues which document
- Regular taxpayers selling taxable goods or services issue tax invoices.
- Composition scheme dealers issue a bill of supply for all their outward supplies, since they pay tax at a fixed rate on turnover rather than collecting it invoice by invoice from customers.
- Regular taxpayers selling exempt goods or services (certain unprocessed food items, specified educational or healthcare services, and other notified exemptions) issue a bill of supply for those specific supplies, even if they issue tax invoices for their other taxable products.
It is worth noting that unregistered persons, who are not required to hold GST registration at all, do not issue either document under GST law, since GST invoicing obligations only apply to registered taxpayers in the first place.
Side-by-side comparison
| Aspect | Tax Invoice | Bill of Supply |
|---|---|---|
| Issued when | GST is charged on the supply | No GST is charged (exempt supply or composition dealer) |
| Shows tax rate/amount | Yes, split by tax type | No |
| Used for buyer's ITC claim | Yes | No, since no tax was charged to claim credit on |
| Issued by composition dealers | Not applicable, composition dealers cannot issue tax invoices | Always, for all outward supplies |
| HSN/SAC required | Yes | Generally yes, for identification, even without tax shown |
| Reported in GSTR-1 | Under taxable supply tables (B2B/B2C) | Reported as exempt/nil-rated turnover, or via composition dealer's own simplified return |
A mixed-business example
Suppose a Chennai-based store sells both packaged snacks (taxable) and certain unprocessed food grains (exempt) to the same walk-in and B2B customers. For the packaged snacks, the store issues a tax invoice showing GST. For the exempt grains, sold to the same or different customers, it issues a bill of supply instead, without any tax component. If a single order includes both taxable and exempt items, businesses often issue one document that functions as a tax invoice for the taxable lines while listing the exempt items separately without tax, provided all mandatory fields for each portion are still present. When in doubt about how to structure a mixed invoice, it is worth checking with a GST practitioner, since the exact presentation can affect how the sale is reported.
What happens if you issue the wrong one
Charging GST and issuing a tax invoice for a genuinely exempt supply means you have collected tax you were not required to collect, which creates its own correction headache. Issuing a bill of supply (with no tax shown) for a supply that was actually taxable understates your output tax liability and can attract interest and penalty on the shortfall once identified. Composition dealers who mistakenly issue a tax invoice showing GST charged to a customer are also stepping outside what their registration permits, since composition taxpayers are not allowed to collect tax separately from buyers.
Where zero-rated exports fit in
It is easy to assume that because an export sale carries no GST payable (when made under a Letter of Undertaking, without payment of integrated tax), it should be documented like an exempt supply with a bill of supply. That is not correct. A zero-rated export, whether under LUT or with IGST paid and later claimed as refund, is still documented with a tax invoice carrying the export/SEZ endorsement, not a bill of supply, because the underlying supply is taxable in nature even though the effective tax collected is nil or refundable. Exempt supplies and zero-rated supplies are treated very differently on paper even though a customer might casually describe both as "tax-free".
This distinction also affects GSTR-1 reporting: export and SEZ tax invoices are reported under their own dedicated tables, separate from the exempt/nil-rated summary that bills of supply feed into. Mixing the two up at the invoicing stage can misstate your zero-rated turnover and complicate any refund claim linked to those exports.
Keeping the two straight in practice
The safest habit is to decide the document type at the item or transaction level, based on whether GST applies, rather than defaulting to one template for everything you sell. OneBooks GST's accounting software lets you record both tax invoices and non-taxable sales entries against the correct GSTIN, so exempt turnover does not get mixed into your taxable sales figures when it is time to prepare GSTR-1. For the full list of fields either document should carry, see our guide to the GST invoice format and mandatory fields. If you are evaluating whether the composition scheme suits your business in the first place, our article on the GST composition scheme covers eligibility and return filing. Questions specific to your account are best routed to support.
Frequently asked questions
Can one business issue both tax invoices and bills of supply?
Yes, a regular taxpayer selling a mix of taxable and exempt goods or services issues a tax invoice for the taxable supplies and a bill of supply for the exempt ones.
Can a composition dealer ever issue a tax invoice?
No. Composition scheme taxpayers are not permitted to collect GST separately from customers, so they issue a bill of supply for all their outward supplies instead.
Does a bill of supply need an HSN code?
Generally yes, for identifying the goods or services, even though no tax rate or amount is shown on the document.
Can a buyer claim input tax credit on a bill of supply?
No. Since no GST was charged on the underlying supply, there is no tax component for the buyer to claim as credit.
What if I mistakenly charge GST on an exempt supply?
The invoice should be corrected, and any tax wrongly collected typically needs to be addressed through a credit note or refund process. It is best to review such cases with a tax professional.
OneBooks GST and this process
Once the source files are in hand, OneBooks GST creates GST invoices with template and PDF output, and carries those invoices through into GSTR-1 preparation.
Validation warnings surface in OneBooks GST before an export is generated, which is cheaper than correcting the same error after filing.
