How to send a GST invoice your customer can pay by UPI

A GST invoice your customer can pay by UPI is a normal tax invoice with every detail the rules ask for, plus a UPI QR code and link that fill in the amount due and the invoice number. Send it on WhatsApp, and mark it paid when the money shows in your bank app.

Picture a physiotherapy clinic in Jadavpur, or a hardware shop in Behala (both examples, not clients). Bills go in a carbon book, office customers ask for "a proper GST bill", and payments arrive on a counter QR with no way to tell who paid for which bill. This guide fixes both halves.

What a GST invoice must show

Rule 46 of the CGST Rules lists what goes on a tax invoice (CBIC). For a small shop or clinic, these are the parts that matter.

• Your details: business name, address and GSTIN.
• A number and the date you issue it (more on numbering below).
• The customer: name, address and GSTIN if they're registered. For an unregistered customer, name, address and state are needed when the bill is ₹50,000 or more, or when they ask for it.
• Each line: a description, the HSN code (goods) or SAC (services), quantity and unit for goods, and the taxable value after any discount.
• The tax: the rate and amount of CGST and SGST, or IGST for a buyer in another state, with the place of supply.
• Reverse charge: whether tax is payable on reverse charge.
• Signature: yours, an authorised person's, or a digital signature.

How many digits of HSN or SAC? If your turnover last year was up to ₹5 crore, show four digits on invoices to registered buyers. You don't have to show the code on invoices to unregistered customers, and above ₹5 crore it's six digits (Notification 78/2020, in force since April 2021).

Rule 46 also says a signature isn't needed on an electronic invoice issued under the IT Act. If you send invoices only as links or PDFs, ask your CA whether yours qualify.

Number and date it properly

Numbering is where carbon books usually go wrong. Rule 46 asks for a consecutive serial number of up to 16 characters, using letters, numbers, hyphens or slashes, and unique for the financial year.

• Pick one pattern and keep it, like INV/26-27/0001.
• Never skip or reuse a number. If an invoice is wrong, cancel it or issue a credit note, and keep both on record.
• If your pattern carries the year, start the new series on 1 April.

For services, the invoice can come after the work, but within 30 days of the service (CBIC invoice rules). A physio course billed at the end of the month is fine. One billed three months later is not.

Add a UPI QR code or link with the amount

A plain QR on the counter makes the customer type the amount. Someone types ₹1,108 instead of ₹1,180, or forgets which bill it was for, and you spend the evening matching payments. Put the QR and a link on the invoice itself, so the amount and invoice number are filled in for them.

The QR and link should carry three things.

1. Your UPI ID, linked to your current account.
2. The amount still due, not the original total if they've paid part.
3. The invoice number in the payment note, like INV/26-27/0142.

That's what the government already asks of very large businesses. Firms with turnover above ₹500 crore must print a dynamic QR code on invoices to consumers. A CBIC circular says it should carry the UPI ID, the balance after any part payment, and the invoice number or a linked order reference (Circular 156/12/2021).

A small shop doesn't have to do this. It's still the easiest way to make every payment match a bill.

What it costs

UPI payments to a merchant carry no merchant discount rate (MDR), which the law has required since 2020. In August 2026 the finance ministry said a nominal, threshold-based MDR may come for some merchant payments, once Parliament passes a bill (The Week, as of November 2026). Ask your bank whether your current account adds any charge of its own.

Bigger businesses: e-invoicing

If your turnover in any year since 2017-18 was above ₹5 crore, e-invoicing applies to you from 1 August 2023 (Notification 10/2023, explained by EY). Those invoices carry a QR code with an invoice reference number from the government system. Most shops and clinics are well below that, but check with your CA.

Send it, then record the payment

1. Make the invoice from saved items, so the price, GST rate and SAC are right every time.
2. Send it as a link or PDF on WhatsApp, or by email for office customers who need it for a claim.
3. The customer opens it, taps Pay, and their UPI app opens with everything filled in.
4. When the money shows in your bank app, mark the invoice paid and note the UPI reference.

A payment to your own UPI ID doesn't tell your billing system anything. Someone has to check and mark it. For a few dozen invoices a month, that takes minutes.

Part payments are common in clinics and repair work. Record each one against the invoice, and the next QR asks only for the balance. Keep a printed copy for anyone who wants paper.

Small sales, advances and bills of supply

Not every sale needs a full tax invoice.

• Under ₹200: if the customer isn't registered and doesn't want an invoice, you can skip it (GST Council flyer). You then issue one consolidated invoice for those sales at the close of each day (CBIC invoice rules).
• Advances for services: GST is payable when you receive an advance for services, not goods, so issue a receipt voucher when someone pays ahead (same flyer). This matters if you sell session packages and memberships.
• Composition scheme or exempt services: you issue a bill of supply instead of a tax invoice. Many health services are exempt from GST, so check with your CA which document your clinic should give.

These rules change from time to time. Treat this as a checklist to take to your CA, not as tax advice.

What to ask your billing app or agency

Whatever you use, from an app to your accountant's software, ask these seven questions.

1. Are numbers gap-free, and is an issued invoice locked against editing?
2. Does it work out CGST and SGST, or IGST for another state, from the buyer's GSTIN?
3. Does each invoice carry a UPI QR and link with the balance due and the invoice number?
4. Can I send it on WhatsApp from my phone?
5. Can I record part payments and see who owes me?
6. Can my CA get each month's GSTR-1 files without retyping?
7. If I leave, can I export every invoice?

If the answer to the first question is no, move on. Corrections belong in credit notes, not in edits. Our page on GST invoicing shows how Pixelvile handles all seven.

If you'd like help

Pixelvile's invoices carry your GST details, a UPI QR and link with the balance and invoice number, go out on WhatsApp, and give your CA the GSTR-1 files each month. Ask for a free audit of how you bill today, or WhatsApp us on +91 62918 31815.