An invoice-cum-bill of supply is a specific option under Rule 46A of the CGST Rules. It may be issued where a registered person supplies taxable as well as exempt goods or services, or both, to an unregistered person. The rule allows one document for those supplies. It does not make every combined retail bill eligible, change the taxability of any line or remove the need to calculate the taxable component correctly.
Confirm that the three facts are present
Check the supplier's registration, the presence of both taxable and exempt supplies and the recipient's unregistered status. A taxable-only sale remains a different situation. A composition supplier's bill of supply should not be relabelled as this combined document simply because some stock items would be taxable under the regular system.
Capture the recipient status when the order is accepted. If a customer later supplies a GSTIN and requests billing to a registration, recheck the document route before issue. Do not treat “GSTIN not typed yet” as proof that the customer is unregistered, particularly for recurring business purchasers whose purchase orders name a registered entity.
Build the document around distinct line treatment
Show the taxable goods or services separately from exempt items. For each taxable line, establish the classification, rate, taxable value and tax head. For exempt lines, use clear treatment that reflects the relevant exemption rather than a vague “tax zero” label that could also mean zero-rated exports or an incomplete rate setup.
The combined heading helps a customer understand why one purchase contains different tax treatment. It cannot replace supporting records. Keep the rate or exemption reference in the item master, including the effective period and conditions. A reader should be able to follow the bill without having to know how the software groups items internally.
Illustrative retail calculation
Suppose an unregistered customer buys taxable supplies worth ₹3,000 after the permitted invoice discount and exempt supplies worth ₹1,500. Assume the taxable supplies have a confirmed aggregate GST rate of 18% and the transaction is an ordinary intra-State supply. CGST is ₹270 and SGST is ₹270. The payable amount is ₹5,040.
| Component | Value | GST | Amount |
|---|---|---|---|
| Taxable supplies | ₹3,000 | ₹540 | ₹3,540 |
| Exempt supplies | ₹1,500 | ₹0 | ₹1,500 |
| Total | ₹4,500 | ₹540 | ₹5,040 |
The example assumes the supplies have been correctly analysed as separately treated items. If the commercial arrangement is a composite or mixed supply, its treatment requires another analysis. Splitting lines on a combined document cannot override the legal character of a bundle sold for one price.
Allocate common discounts carefully
A basket discount can create an avoidable calculation problem. If the seller grants ₹450 off a ₹3,000 taxable and ₹1,500 exempt basket, allocating all ₹450 to the taxable lines merely to reduce GST would need commercial support. A proportionate allocation, where consistent with the offer terms, would assign ₹300 to taxable supplies and ₹150 to exempt supplies.
That would leave ₹2,700 taxable and ₹1,350 exempt. At the same assumed 18% rate, GST would be ₹486 and total payable ₹4,536. Retain the offer terms and calculation method. The important control is that the invoice reflects the actual agreed discount, not an unexplained distribution generated at checkout.
Preserve the information needed for later reporting
Keep separate taxable and exempt totals in the sales records even though the customer receives a single document. Bank or UPI collections will normally match the combined amount; tax reporting still needs the components. Reconcile the collection against the invoice total first, then reconcile the invoice's supply categories against the sales register.
Returns and exchanges also require line-level traceability. If the customer returns only an exempt item, staff should not reverse tax from the original taxable component. If a taxable item is returned, identify its original value and tax rather than using a percentage of the entire basket. Record the original document reference in the return record.
Review design and staff instructions together
Test whether long descriptions, multiple rates and discounts remain readable in the print or PDF format. Avoid putting one GST rate in the footer when different taxable lines have different rates. Label tax subtotals so customers can see which values they cover. Keep prescribed identities, numbering and date details intact.
Give sales staff a short decision rule: use the combined route only after recipient status and the taxable/exempt mix are confirmed. An unclear customer classification should enter a review queue before the document is finalised. Once eligibility is established, the invoice-cum-bill of supply can make an ordinary mixed basket easier to read while keeping the taxable calculation and exempt value distinguishable throughout the records.
For a printed retail receipt, keep an accessible full copy where a narrow roll cannot display all details comfortably. Test a basket containing a return, an exempt line and a taxable line before adopting the format. The same document identity should remain visible in the sale and return records.
Record an eligibility decision for unusual baskets
An ordinary shop sale may be straightforward, but institutional orders and recurring service packages deserve a brief review note. Record whether the recipient is unregistered, which lines are exempt and why a combined document was selected. Where a package price includes admission, equipment and supplies, analyse the arrangement before treating each component independently. The record can be short: order reference, commercial structure, confirmed treatment and reviewer. This gives the next employee something more reliable than copying the last invoice.