How to Make a Legal Invoice in India: 7 Simple Steps

A client pays an invoice quickly when it is correct, and the tax office accepts it without questions when it is complete. Many small businesses get neither because nobody explained the rules in plain language.

The advice here covers a normal business-to-business or business-to-consumer sale. Special cases such as exports, composition dealers and e-commerce operators have extra rules, so ask your Chartered Accountant if one of them applies to you.

how to make a legal invoice: What makes an invoice legal in India

The law sets the content, not the design. Rule 46 of the CGST Rules lists the particulars a tax invoice must carry, and you can read the full wording of Rule 46 on GSTZen. The rule runs from clause (a) to clause (s), and you fill in only the clauses that apply to your sale.

A legal invoice, then, is any document that carries those details accurately, in a clear layout, issued by a registered person at the right time.

The core details are your name, address and GSTIN, a unique serial number, the date, the buyer’s details, a description of the goods or services, the quantity, the value, the tax rate and the tax amount.

Everything else in this guide is a way to get those details right and keep them consistent from one invoice to the next.

Step 1: pick the right document

Before you write a single line, decide what kind of document the sale needs. A registered supplier of taxable goods or services issues a tax invoice. A supplier who sells only exempt goods or services, or who runs under the composition scheme, issues a bill of supply.

A person liable under reverse charge issues a payment voucher when paying an unregistered supplier.

Registration comes first. The usual GST registration limit is ₹40 lakh of turnover for goods and ₹20 lakh for services, and it is lower in some special category states.

Anyone who sells across state lines normally has to register whatever the turnover. If you are below the limit and unregistered, you cannot charge GST, so your document is a simple invoice with no tax lines.

One more small rule helps with tiny sales. The GST Council guide notes that you do not need an invoice for a supply below ₹200 under certain conditions, though you will still want a record. The difference between an invoice and a bill explains how these documents relate to each other.

Step 2: gather both sets of details

how to make a legal invoice: Collect your own details first and keep them saved so you never retype them. You need your registered business name, address, GSTIN and, if you use one, a logo. Then collect the buyer’s details.

A registered buyer needs their legal name, address and GSTIN on the invoice, because the buyer uses that GSTIN to claim input tax credit. A wrong digit in the GSTIN can block that claim, so check it against the buyer’s registration certificate.

An unregistered buyer is simpler. If the taxable value is ₹50,000 or more, you record the buyer’s name, address, delivery address and state name and code. Below ₹50,000, you record those details only if the buyer asks. Retail shops use that second rule all day long.

Step 3: set the invoice number

If you wonder how to make an invoice number that passes the rules, the answer is short. Give each invoice a number that is unique within the financial year, uses only letters, digits, hyphens and slashes, and runs to at most 16 characters. You can run one series or several, for example one per branch.

A pattern such as INV/26-27/0001 works well. It names the document type, the financial year and a running count, and it fits inside 16 characters. Start the count again each April if you want, as long as the full number never repeats within the year.

Never skip a number silently. If you cancel an invoice, keep the number and mark it cancelled, so the sequence has no unexplained gaps.

Sample layouts with working numbers appear in our walkthrough of free invoice examples.

Step 4: describe what you sold

Write each line so a stranger understands it. “Website design, five pages” says more than “Services”. Add the quantity and the unit for goods, the rate, any discount and the amount.

You also need a classification code. Goods use an HSN code and services use a SAC code. Since 1 April 2021, a business with turnover up to ₹5 crore has to show at least 4 digits on B2B invoices, and a business above ₹5 crore has to show 6 digits. Shorter codes get rejected by some buyer systems, so use the longer code when you know it.

Show discounts before tax. If you give a 5% trade discount on ₹12,000, the taxable value is ₹11,400, and the tax applies to that smaller number.

Step 5: work out the tax

The place of supply decides the tax type. When you and the buyer are in the same state, split the tax into CGST and SGST in equal halves. When the sale crosses a state border, charge IGST as one line. Show the rate and the amount for each.

Check the rate itself. On 22 September 2025, the GST Council’s revised structure took effect and the 12% and 28% slabs went away. Most goods now sit at 5% or 18%, with a 40% rate for a short list of luxury and sin goods, and some essentials are at nil.

Old templates often still carry the old slabs, so always confirm the rate for your product on the current rate schedule.

A quick example shows the arithmetic. Services worth ₹30,000 in one state at 18% produce ₹2,700 of CGST and ₹2,700 of SGST, and the invoice total is ₹35,400. Write the reverse charge status too. For most sales the answer is “No”.

Step 6: issue it on time

Timing is part of being legal. For goods, you issue the invoice before or at the time you remove the goods or hand them over.

For services, you may issue it before or after the work, but if it comes after, you have 30 days from the date of supply. Banks, insurers and other financial institutions get 45 days.

Continuous supplies follow their own timing. A monthly service contract usually needs an invoice by the due date in the contract, or at payment if the contract names none.

Goods sent on approval need an invoice at supply or within six months of removal, whichever comes first.

Copies matter as well. For goods you prepare three copies: the original for the buyer, the duplicate for the transporter and the triplicate for your records. For services you prepare two. Electronic invoices make this routine, but you should know why the copies exist.

If goods travel before the sale is final, a dispatch paper fills the gap. The delivery challan maker produces that slip with the vehicle number and e-way bill reference.

Step 7: add payment terms and get paid

People often ask how to make an invoice for payment that actually gets paid. Put the due date near the top, not buried in the footer. Add your bank name, account number and IFSC, or add a UPI ID and a QR code so the buyer can pay from a phone in seconds. State the late payment terms in a short, polite line.

Payment speed matters more than it used to. Under Section 43B(h) of the Income-tax Act, a buyer who pays a micro or small enterprise supplier late cannot deduct that expense until the year of actual payment. The time limit is 45 days with a written agreement and 15 days without one.

Many large buyers now chase their small suppliers for tight due dates because of this rule, so write a realistic one on your invoice and ask your CA how it affects you.

If you are still negotiating the price, send a quote first. A proforma invoice also works when the buyer needs a document to arrange an advance payment or customs clearance.

E-invoicing for larger businesses

Once your aggregate turnover crosses ₹5 crore in any financial year from 2017-18 onwards, you generate B2B invoices through the government’s invoice registration portal.

Notification 10/2023-Central Tax set that threshold with effect from 1 August 2023. The portal returns an invoice reference number and a QR code, and your invoice must carry both.

An e-invoice does not need a signature, because the registration itself authenticates it. Smaller businesses can ignore the portal and keep issuing invoices the usual way. Check your turnover every year, because the obligation starts the year after you cross the line.

How to make an invoice receipt after payment

how to make a legal invoice: An invoice asks for money. A receipt confirms you got it. When a client pays in full, send a short receipt that names the invoice number, the amount, the date and the payment mode. For a part payment, state the balance still due.

A cash payment deserves extra care. The cash receipt maker adds a signature slot and a revenue stamp area, which helps when the amount is large. Keep the receipt with the invoice in the same folder. Match each receipt to its invoice number, and your books reconcile without a hunt.

A quick checklist for a small business

If you run a small shop or a one-person practice, print this and keep it near your computer. It covers how to make invoices for a small business without a finance team.

• • Save your business name, address and GSTIN in your billing tool once.

• • Number invoices in a single series and never reuse a number in a financial year.

• • Record the buyer’s GSTIN for every B2B sale and verify it.

• • Use the right tax type: CGST plus SGST inside the state, IGST outside it.

• • Show discounts before tax and show the taxable value on its own line.

• • Issue goods invoices at dispatch and service invoices within 30 days.

• • Add the due date, bank details or a UPI QR code.

• • Download a PDF and keep a copy for at least the period your CA advises.

The fastest way to follow that list is a tool that remembers your details. The GST invoice generator keeps the layout fixed and calculates the tax for you, so you only enter the lines.

Common mistakes that make an invoice invalid

• • Missing GSTIN or a wrong digit in it, which blocks the buyer’s input tax credit.

• • A repeated or skipped invoice number.

• • The wrong tax type for the place of supply.

• • Tax calculated on the full price instead of the discounted value.

• • An out-of-date tax rate carried over from an old template.

• • A service invoice issued 40 days after the work, past the 30-day limit.

• • No HSN or SAC code, or one with too few digits for your turnover band.

None of these mistakes is hard to avoid. Most come from retyping details by hand each time, which is exactly what a saved template prevents.

Questions people ask

Can I make a legal invoice in Word or Excel?

Yes. The law cares about the content, so any file that carries the required details is valid. The risk is manual errors in numbering and tax, which a calculator tool removes.

Do I need a signature on the invoice?

A paper invoice needs the supplier’s or an authorised person’s signature. An electronic invoice does not need one under the IT Act rule, though many businesses add a digital signature anyway.

What is the difference between an invoice and a bill?

In everyday talk they mean the same thing, but GST treats a tax invoice and a bill of supply as different documents. Our short explainer on the invoice and bill difference covers when each one applies.

How long should I keep invoices?

Keep them for the period the law requires for records, which your Chartered Accountant can confirm for your case. Store the PDF and the matching receipt together so an audit takes minutes, not days.