How do I send a GST invoice to a customer on WhatsApp, and get paid faster?

The fastest way to send a GST invoice on WhatsApp is to send it from your billing app as a link the customer can open and pay from, not as a PDF you forward by hand. The invoice still has to be a proper tax invoice, so start with what it must show, then make paying it a single tap.

What must a GST tax invoice show?

A GST-registered business issues a tax invoice. The contents are set by Rule 46 of the CGST Rules, 2017 (published by CBIC at cbic-gst.gov.in; the GST portal is gst.gov.in). In plain terms, every tax invoice needs:

Must show	Note
Your name, address and GSTIN	Of the registration making the supply
A serial number, unique for the financial year	Up to 16 characters: letters, digits, - and /
Date of issue
The customer's name and address, and GSTIN if registered	A business customer needs this to claim input tax credit
HSN (goods) or SAC (services) code	How many digits depends on your turnover; ask your CA
Description, quantity and unit
Taxable value, after any discount
Rate and amount of tax: CGST + SGST, or IGST
Place of supply, with the state	Decides which tax applies
Signature of the supplier or an authorised person

Keep it generic and correct: these are the standard rules. Special cases (exports, reverse charge, e-invoicing above the notified turnover) have their own requirements, and your CA should confirm them.

CGST + SGST or IGST: which one goes on the bill?

It depends on whether the supply stays inside your state.

Say an electrician in Madurai installs a ceiling fan and some wiring worth ₹20,000 before GST, taxed at 18%:

Customer is in	Tax on the bill	Total
Tamil Nadu (same state)	CGST ₹1,800 + SGST ₹1,800	₹23,600
Karnataka (another state)	IGST ₹3,600	₹23,600

The total is the same; the split is different. BizOS decides it by comparing the state code in your GSTIN with the state code in the customer's GSTIN. A customer with no GSTIN is treated as being in your state. BizOS stores no state for customers without a GSTIN, so if you regularly sell to unregistered buyers in other states, have your CA check those bills.

If you agree prices including GST ("the job is ₹23,600"), BizOS lets you type ₹23,600 and works out the taxable value and the tax underneath, so the bill totals exactly what you quoted. That setting is on by default for a registered business. See GST billing.

Why not just make a PDF and forward it?

Plenty of owners still do this: make the bill in a desktop program or a template, save the PDF, open WhatsApp, find the contact, attach, send. It works. The cost shows up later.

	PDF made and forwarded by hand	Sent from the billing app
Time per bill	Several steps across two apps	Issue, then Send
Way to pay	Customer copies your UPI ID or account number	UPI QR for the balance, and a Pay now button if you use online payments
Do you know it was seen?	Only from the blue ticks	You can see when the link was first and last opened
When they pay	You check the bank and mark it paid yourself	Online payments mark the bill paid; cash and UPI are recorded in a tap
Reminders	You remember, or you don't	Sent on a schedule around the due date (with the Billing base)
Lost the file?	Make it again	Re-send the same link

The forwarded PDF is just a picture of the bill. The link is the bill itself, with its live balance.

How do I send a GST invoice on WhatsApp from BizOS?

1. Set up GST once. In Settings → Business → Profile & GST, switch on GST-registered and enter your GSTIN. Add HSN or SAC codes to your items, and save a business customer's GSTIN on their record.
2. Add your UPI ID and bank details in Settings → Selling → Payments. The primary UPI ID is the one that prints.
3. Make the invoice. Start from scratch, an accepted quote, a finished job or a saved template. GST is applied at each line's rate; there is no per-bill GST switch.
4. Issue it. Issuing fixes the number and the GST, moves stock and starts the reminder clock. A draft is never sent to a customer.
5. Send on WhatsApp. The customer gets a link to your invoice. You can also download or print the PDF, in any of the document designs.

Until you connect your own WhatsApp Business number, BizOS sends from a shared BizOS number (50 messages a month on the free platform). Once you connect your own number, bills go out with your business name, and you can keep using the WhatsApp Business app on your phone. See WhatsApp setup.

What does the customer see when they open it?

The link opens in any browser, with no app and no login. It shows your invoice as your business: your logo, colours, terms and seller details. On a GST invoice the PDF can show the full GST breakup (the default) or prices including GST; a business customer claiming input tax credit needs the breakup, which is always one click away in the PDF menu.

To pay, the customer gets:

• A UPI QR for the balance, when your UPI ID is on file. Any UPI app can scan it.
• A Pay now button, when you connect your own Razorpay account. The customer pays by UPI or card, the money settles into your account, and the invoice turns Paid by itself. BizOS never routes the money through an account of its own.

What happens after the customer pays?

Every payment gets a numbered receipt (RCPT-0001 onwards by default). A receipt acknowledges money only: it prints the amount in figures and in words, the invoice it was against and the balance left, and no GST, because the tax was charged on the invoice.

• A part payment moves the invoice to Partial, with the balance still visible. Each instalment has its own receipt.
• Money paid before the bill, or more than the bill, is held as the customer's credit and applied when you choose. See Receipts, advances & credit.
• BizOS does not yet send receipts on WhatsApp automatically; you download or share the receipt PDF.

For the customers who don't pay on time, see how to chase payments on WhatsApp without annoying customers.

Tips to get paid faster

• Send the bill the day the work is done. A bill sent a week later is paid a week later.
• Always give a way to pay. A saved UPI ID puts a QR on the invoice; without one the customer has to ask.
• Set a due date. Reminders count from it. Payment terms default to 30 days in Settings → Selling → Invoices & quotes; shorten them for walk-in customers.
• Give business customers the GST breakup copy. They need it for input tax credit, and a bill they can't book is a bill they delay.
• Collect on site. A field technician can open the job's invoice and its UPI QR in the phone app, so the customer pays before the van leaves. See billing on the job for electricians and plumbers.

When is BizOS the wrong tool for this?

BizOS is a good fit if you are an Indian shop, distributor or service business billing in rupees, your customers are on WhatsApp, and you want the bill, the payment and the follow-up in one place, with your CA keeping the books.

It is the wrong tool, or only part of the answer, if:

• You must issue e-invoices. BizOS does not generate IRNs or the e-invoice QR code.
• You need e-way bills generated. Challans record the transporter and vehicle, but BizOS files nothing.
• You want returns filed for you. BizOS exports GSTR-1 for you or your CA to upload; it does not file GSTR-1 or prepare GSTR-3B.
• You are on the composition scheme or QRMP, or bill exports and SEZ supplies: BizOS has no mode for these.
• You bill in a currency other than rupees.

If that fits, start free and send your first GST invoice on WhatsApp today.