Quick answer: To create an invoice, write your business name, address and GSTIN; give the invoice a unique number and date; add the customer's name, address, GSTIN (if registered) and place of supply; list each item with its HSN or SAC code, quantity, rate and taxable value; add CGST and SGST (same state) or IGST (different state); show the total in figures and words; and sign it. You can do this in a spreadsheet, in a free invoice generator or in billing software that numbers and files invoices for you.
This guide walks through each step for Indian businesses, explains which invoice to use when, and lists the mistakes that most often lead to rejected input tax credit or delayed payments.
What an invoice is and why the format matters
An invoice is the document a seller issues to ask for payment and to record a sale. Under GST it does more than that. The buyer uses your tax invoice to claim input tax credit, you report it in GSTR-1, and a tax officer can ask for it years later. If a mandatory field is missing, the buyer's credit can be questioned and your payment gets held until you issue a corrected invoice.
That is why "just send a bill" is not enough once you are GST registered. The contents of a tax invoice are set by Rule 46 of the CGST Rules, and the time limits and number of copies by Section 31 and Rule 48.
Beautiful GST invoices with your signature and stamp, quotations to credit notes, inventory, UPI collection and 30+ reports.
Start free See the demoWhich invoice should you create?
| Document | When to use it | Charges GST? |
|---|---|---|
| Tax invoice | A registered supplier sells taxable goods or services | Yes |
| Bill of supply | Composition dealers, or supplies that are exempt or nil-rated | No |
| Proforma invoice | A quote or advance request before the actual sale | Not a tax document |
| Export invoice | Goods or services supplied outside India | Marked with or without payment of IGST |
| Credit note / debit note | Reducing or increasing the value of an invoice already issued | Adjusts GST |
| Delivery challan | Goods move without a sale, such as job work or approval | No |
If you are unsure about the difference between a quote and a real invoice, read proforma invoice vs tax invoice. For corrections after a sale, see our guide to the credit note under GST.
Step 1: Add your business details
Start at the top with the details of the supplier:
- Legal or trade name of the business
- Full address, including state
- GSTIN, the 15-character number whose first two digits are your state code
- Phone, email and logo (optional, but they help the customer pay faster)
Step 2: Number and date the invoice
Every invoice needs a consecutive serial number of up to 16 characters, unique for the financial year. Letters, numbers, hyphens and slashes are allowed. A format such as INV/2026-27/001 works well because the year resets cleanly on 1 April. You can run separate series for branches or document types, as long as each series is continuous and reported correctly.
Add the invoice date, and a due date if you offer credit.
Step 3: Add the customer and place of supply
For a registered buyer, show the name, address and GSTIN. For an unregistered buyer, the name and address are required when the taxable value is ₹50,000 or more.
Then fill in the place of supply with the state name and code. This decides the tax type:
- Seller and place of supply in the same state: charge CGST and SGST (or UTGST), half the rate each
- Different states: charge IGST at the full rate
Getting this wrong is the single most common GST invoice error, because tax paid under the wrong head has to be paid again under the correct one and the first amount refunded later.
Step 4: List items with HSN or SAC codes
For each line, include:
- Description of the goods or services
- HSN code (goods) or SAC code (services)
- Quantity and unit, such as Nos, Kg or Hours
- Rate per unit
- Discount, if any
- Taxable value
- GST rate and tax amount
The number of HSN digits depends on your turnover. Businesses with aggregate turnover up to ₹5 crore in the previous year must show at least 4 digits on B2B invoices. Above ₹5 crore, 6 digits are mandatory on all invoices.
Step 5: Calculate GST and totals
Multiply each taxable value by its rate. If you give a discount on the invoice itself, reduce the taxable value before calculating tax. Then add up:
- Subtotal and discounts
- Taxable value
- CGST + SGST, or IGST, shown rate by rate
- Round-off, if you round to the nearest rupee
- Invoice total in figures and in words
Example: ₹25,000 of design services at 18% and ₹6,000 of printing at 5%, both within Delhi. CGST is ₹2,250 + ₹150 and SGST is the same, so total GST is ₹4,800 and the invoice total is ₹35,800. Check your own figures with the GST calculator, or read how to calculate GST for inclusive prices and reverse calculations.
Step 6: Add terms, bank details and signature
Close the invoice with:
- Whether tax is payable on reverse charge (Yes or No)
- Payment terms, bank account or UPI ID
- Signature or digital signature of the supplier or authorised person
A UPI QR code on the invoice is not mandatory for most businesses, but it makes it far easier for customers to pay on the day they receive it.
Step 7: Issue it on time, in the right number of copies
When: for goods, issue the invoice before or at the time of removal or delivery. For services, issue it within 30 days of the supply (45 days for banks and financial institutions).
Copies: goods need three copies, marked original for the recipient, duplicate for the transporter and triplicate for the supplier. Services need two, original for the recipient and duplicate for the supplier.
Do you need an e-invoice?
If your aggregate turnover crossed ₹5 crore in any financial year since 2017-18, your B2B invoices must be registered on the Invoice Registration Portal (IRP) to receive an IRN and a signed QR code. Businesses with turnover of ₹10 crore or more must report each e-invoice to the IRP within 30 days of the invoice date. An e-invoice is still your own invoice; the portal validates and signs it. Below the threshold, a correctly formatted PDF or printed invoice is enough.
Ways to create an invoice
| Method | Good for | Watch out for |
|---|---|---|
| Excel or Word template | A few invoices a month | Manual numbering, formula errors, no payment tracking |
| Free online invoice generator | Quick one-off GST invoices as PDF | You keep your own records and numbering |
| GST billing software | Regular invoicing, inventory, reminders | Choose one that exports GSTR-1 data |
Our free invoice generator builds a Rule 46 style tax invoice, proforma invoice or bill of supply in your browser, splits CGST, SGST or IGST from the place of supply, writes the amount in words and saves to PDF. Nothing you type is uploaded.
Common invoice mistakes
- Wrong tax head: IGST charged on a same-state sale, or CGST/SGST on an inter-state one
- Broken numbering: gaps, duplicates or reused numbers after 1 April
- Missing buyer GSTIN: the buyer cannot claim credit on an invoice without it
- No HSN or wrong digits: flagged when GSTR-1 is filed
- Amount in words missing or wrong: looks minor, but it is the first thing auditors check
- Invoice issued late for services: after 30 days you are out of time
When to move from templates to software
Spreadsheets break down once you raise more than a few dozen invoices a month or need to track who has paid. MizUp Finance creates GST invoices with UPI QR, digital signature and stamp, turns quotations into invoices, records purchase bills and multi-warehouse stock, and gives you GSTR-1 reports. It has a free plan for small businesses; see pricing.
Before you file, review the full list of fields in the GST invoice format under Rule 46 and keep the delivery challan format handy for goods that move without a sale.
Frequently asked questions
How do I create an invoice for free?
Use a free online invoice generator such as the MizUp invoice generator. Enter your business and customer details, add items with HSN or SAC codes and GST rates, and save the invoice as a PDF from the print window.
What must a GST invoice contain?
Supplier name, address and GSTIN; a unique serial number of up to 16 characters; date; buyer name, address and GSTIN if registered; place of supply; HSN or SAC; description, quantity and value; taxable value; GST rate and amount split into CGST/SGST or IGST; total; reverse charge indication; and signature.
When should I charge IGST instead of CGST and SGST?
Charge IGST when the supplier and the place of supply are in different states or union territories. Charge CGST plus SGST or UTGST when both are in the same state.
What is the time limit to issue an invoice for services?
Within 30 days from the date of supply of services. Banks and financial institutions get 45 days.
Is e-invoicing mandatory for my business?
E-invoicing is mandatory for B2B invoices if your aggregate turnover exceeded ₹5 crore in any financial year from 2017-18 onwards. Below that, a correctly formatted regular invoice is enough.
