How to Make a GST Bill on Mobile for Free (Step by Step, 2026)

Ten years ago a GST bill meant a printed bill book or a desktop in the back office. Today most small shops in India make their bills on the same phone they use for UPI, and the question has shifted from "can I make a GST bill on my mobile?" to "how do I make one that is actually correct?"

This guide answers the second question. It covers what to have ready before your first bill, the three ways to make a GST bill on a phone and what each one costs you, a step-by-step walkthrough, and the mistakes that most often make a mobile bill invalid. If you only want the short version, it is right below.

Quick answer: how to make a GST bill on mobile

1. Install a GST billing app (or open a template or online generator; the trade-offs are compared below).
2. Enter your business details once: name, address, GSTIN, state, and your UPI ID or bank details.
3. Save your items with their HSN code and GST rate, and your regular customers with their GSTIN and state.
4. Create the bill: pick the customer, add items and quantities, and check the place of supply so the tax is split correctly into CGST + SGST or IGST.
5. Save and share: send the PDF on WhatsApp or print it, and collect payment by UPI.

The first bill takes about ten minutes, almost all of it setup. After that, a bill takes under a minute.

What you need before your first GST bill

Collect these before you start, so the first bill is not a scramble:

Detail	Where it comes from	Why the bill needs it
Business name and address	Your GST registration certificate	Must match your registration exactly
GSTIN	GST registration (15 characters)	Mandatory on every tax invoice
Your state and state code	First two digits of your GSTIN	Decides CGST + SGST or IGST
HSN or SAC code for each item	GST portal search, your supplier's bill, or your CA	At least 4 digits on B2B bills if turnover is up to ₹5 crore
GST rate for each item	CBIC rate notifications, or your CA	Since 22 September 2025, mostly 5% or 18%
Customer's name, GSTIN and state	The customer	Their GSTIN lets them claim input tax credit
UPI ID or bank account	Your bank or UPI app	So the customer can pay from the bill

The HSN code is the one people skip, and it is the one that later causes trouble in GSTR-1. Our guide to the GST invoice format explains how many digits you need and what else Rule 46 requires on the bill.

Do you need a GST bill, or a plain bill?

Not every business that bills customers should issue a GST tax invoice:

• You are GST-registered under the regular scheme: issue a tax invoice that charges GST. This is what the rest of this guide covers.
• You are under the composition scheme: you cannot charge GST to customers. Issue a bill of supply instead, stating that you are a composition taxable person not eligible to collect tax.
• You sell only exempt goods such as fresh vegetables or unpackaged grains: issue a bill of supply, not a tax invoice.
• You are not registered for GST: you cannot show or collect GST at all. A clean bill with your name, the items and the total is enough. A billing app is still useful for numbering, records and UPI collection; just turn GST off on the bill.

Charging GST without a valid registration, or charging it as a composition dealer, is a serious error. Settle which category you are in before your first bill.

How to find the HSN code and GST rate for your items

If you do not know an item's code, there are three reliable routes:

1. Your supplier's purchase bill. For goods you resell, the HSN code on the invoice you received is usually the right one, and it is the fastest place to look.
2. The GST portal's HSN/SAC search. Search by product name or code on the official GST services site.
3. Your chartered accountant, especially for items that changed slab in September 2025 or that could fall under more than one heading.

Save each code once in your app's item list and you never have to look it up again.

Three ways to make a GST bill on your phone

You can make a valid GST bill on a phone in three ways. They differ less in the bill they produce than in how much work the next 500 bills take.

	Billing app	Online invoice generator	Excel or Word template
Works offline	Depends on the app	No	Yes
Invoice numbering	Automatic	Usually manual	Manual
CGST/SGST vs IGST split	Automatic in good apps	Usually manual	Formula you maintain
Saved items and customers	Yes	Sometimes, with an account	Copy and paste
Share on WhatsApp	Built in	Download, then share	Export to PDF, then share
Monthly GST summary	Yes, in most apps	Rarely	You build it
Cost	Free to ₹4,000+ a year	Usually free	Free

Templates are fine if you make a few bills a month. On a small phone screen, though, editing a spreadsheet at the counter is slow, and the classic errors creep in: last month's file copied with the old invoice number, or the IGST formula overwritten.

Online generators produce a clean PDF but need a working internet connection for every bill, and you usually manage the numbering yourself. Your customers' details also sit on someone else's server.

Billing apps do the repetitive parts for you, including numbering, the tax split, the saved catalogue and the monthly summary. The things to check before choosing one are whether it works when the network drops and what its free plan actually includes. We compared the main options honestly in the best GST billing apps for 2026.

Step by step: making a GST bill in BillZap

The walkthrough below uses BillZap, our free GST billing app for Android. It is free with no paid tier, needs no account, and works fully offline. The same steps apply, in spirit, to any good billing app.

Step 1: Install the app

Download BillZap from Google Play. It runs on Android 7.0 and above and is about 32 MB. There is no sign-up, OTP or email: you open it and start setting up your shop.

Step 2: Set up your shop (once)

Enter your business name, address, GSTIN and state, then your UPI ID and bank details. The state matters most here, because the app compares it with the place of supply of every bill to decide the tax split. The UPI ID matters next, because it is what turns every unpaid bill into a scan-and-pay QR code.

Step 3: Set your invoice number series

In settings, choose an invoice prefix, for example SMH- or BZ-. Every bill then gets the next number in that series automatically. GST rules require numbers that are consecutive, unique for the financial year and no longer than 16 characters, so keep the prefix short. If you are moving from another app or a bill book mid-year, pick a prefix you have never used, so the new series cannot repeat an old number.

Step 4: Add your items with HSN codes and rates

Add the products or services you sell most, each with its HSN or SAC code and GST rate. You do this once per item. BillZap suggests a GST rate from the item name, but confirm it, especially for anything that changed slab in the September 2025 reform. From then on, every bill that includes the item prints its code and charges its rate without you typing either again.

Step 5: Add your regular customers

Save each regular business customer with their name, phone number, GSTIN and address. When you start a bill and type the first letters of their name, the app fills in the rest. For walk-in customers, you can bill without saving anyone.

Step 6: Create the bill by tapping or speaking

Start a new invoice, pick the customer and add items with quantities. If typing at the counter is slow, use voice billing: say the item and amount in any of 12 Indian languages (English, Hindi, Tamil, Telugu, Kannada, Malayalam, Marathi, Gujarati, Bengali, Punjabi, Odia or Urdu) and the line fills in. Add a delivery charge if there is one.

Step 7: Check the place of supply and the tax split

The place of supply starts as your own state. If the goods are going to another state, change it, and the tax switches from CGST + SGST to IGST. BillZap shows which split it has chosen before you save, so a wrong split is caught on the screen, not in your return. If you are unsure which applies, for example on an over-the-counter sale to a customer from another state, our guide to CGST, SGST and IGST has worked examples.

Step 8: Save, share and get paid

Save the bill and it becomes a clean PDF with a correctly rendered ₹ symbol. From the same screen you can:

• Share it on WhatsApp, with a UPI payment link attached if it is unpaid
• Print it on a WiFi or Bluetooth printer
• Show the UPI QR code printed on the bill, so the customer pays from any UPI app straight into your bank account

BillZap is not a payment gateway. The money goes directly from the customer's UPI app to your account.

Step 9: Close the day and hand over the month

At closing time, the day-close screen shows cash in, UPI in, expenses out and the cash you should have in the drawer. At month end, export the GST summary, with taxable value, CGST, SGST and IGST laid out for GSTR-1, as a PDF or CSV and send it to your accountant.

What your finished bill should contain

Whatever app or template you use, a correct GST tax invoice made on a phone carries:

• Your name, address and GSTIN, and the buyer's GSTIN if they are registered
• A unique invoice number and the date
• For each line: description, HSN or SAC code, quantity, unit and taxable value
• The GST rate and amount, split into CGST + SGST, or IGST
• The place of supply for inter-state sales, and whether reverse charge applies
• The total, plus optional payment details such as a UPI QR code

A bill sent as a PDF from your phone is an electronic invoice, and under Rule 46 an electronic invoice does not need a physical signature.

Tips by type of business

Kirana and retail counters. Speed matters more than anything. Save your fastest-moving items first, use voice billing during rush hours, and keep the UPI QR on every bill, since most customers already have a UPI app open. For small sales where the customer does not want a bill, the rules allow one consolidated tax invoice at the end of the day, but most shops find individual bills easier to reconcile.

Wholesalers and distributors. Your buyers are mostly registered, so their GSTIN on the bill is non-negotiable; a wrong GSTIN blocks their credit and they will call you about it. Double-check the place of supply on every outstation order, and use the invoice ageing report to chase payments: BillZap sorts unpaid bills into 0–30, 31–60, 61–90 and 90+ day buckets.

Service providers. Use SAC codes, which begin with 99, instead of HSN codes. Issue the bill within 30 days of finishing the service. For a registered client in another state, the place of supply is the client's location, so the bill carries IGST.

Mistakes that make a mobile GST bill invalid

• No HSN code, or too few digits on a B2B bill
• One "GST 18%" line instead of separate CGST and SGST amounts on an intra-state bill
• IGST on an over-the-counter sale just because the customer is from another state
• Repeating an invoice number after switching apps or reinstalling one without restoring a backup
• A typo in the buyer's GSTIN, which stops their input tax credit
• An outdated GST rate, such as 12% or 28% on items that moved slab in September 2025
• No backup: a phone is easy to lose, and the bills on it are records you must keep

On the last point, take regular backups. BillZap saves a backup file you keep wherever you like, such as Google Drive, email or a computer, and restores it on a new phone. It also has an app lock with PIN or fingerprint, so a borrowed phone does not mean borrowed books.

When a phone app is not enough

A mobile billing app covers most small businesses, but two GST requirements need more:

• E-invoicing. If your aggregate turnover has crossed ₹5 crore in any year since 2017-18, your B2B invoices must be registered on the Invoice Registration Portal for an IRN and QR code. You will need software that connects to the IRP.
• E-way bills. Moving goods worth more than ₹50,000 in a consignment generally needs an e-way bill, and some states set their own limits for movement within the state. Many shops below that value never need one; wholesalers usually do.

BillZap does not generate e-invoices or e-way bills. If you need either, choose a tool that supports them. Our comparison of GST billing apps shows which ones do.

FAQ: making a GST bill on mobile

Can I make a GST bill on my mobile phone?

Yes. A GST tax invoice can be created and issued electronically from a phone, as long as it contains everything Rule 46 of the CGST Rules requires. An electronic invoice does not need a physical signature.

Which app is best for making a GST bill on mobile for free?

It depends on what you need. For counter billing with no subscription and no internet dependence, BillZap is free with no paid tier and works fully offline. If you need e-invoicing, e-way bills or several devices, a paid app such as Vyapar or myBillBook may fit better.

How do I make a GST bill without internet?

Use a billing app that stores your data on the phone instead of in the cloud. Offline-first apps let you create, save, print and share bills with no connection. Apps that sync to a server may stop working or queue bills when the network drops.

Is a GST bill made on mobile valid?

Yes, provided it carries the mandatory particulars: both GSTINs where applicable, a unique invoice number, date, HSN or SAC codes, taxable value, and the correct CGST + SGST or IGST split. The method used to make the bill does not matter; its contents do.

How do I send a GST bill to a customer on WhatsApp?

Save the bill as a PDF and share it from your billing app's share button, or from your files to WhatsApp. Billing apps such as BillZap do this in one tap, and can attach a UPI payment link to unpaid bills.

Do I need a computer for GST billing?

No. For billing, a phone is enough. Your accountant may use a computer for filing returns, and you can send them your monthly GST summary as a PDF or CSV from the phone.

The bottom line

Making a GST bill on mobile is easy. Making a correct one every time comes down to three habits: set up your details and HSN codes once, let the app split CGST, SGST and IGST from the place of supply, and keep a backup. A template can do the job for a handful of bills; for daily counter billing, an app that works offline saves you time and mistakes.

If you want to try it on your next bill, BillZap is free on Google Play, with no account, no subscription and no internet needed.

This guide explains GST billing in plain language and is not tax advice. Confirm item-specific GST rates and thresholds with your chartered accountant.