Most people searching for booking invoice are about to issue the wrong document, and the cost of that is not discovered until a return does not reconcile. This page sets out what it is, when it applies, what it must carry, and which document you may actually need instead.
The document family, in one place
Almost every mistake in this area comes from treating these as different names for an invoice. They are not; they do different things and some of them must not carry tax at all.
A tax invoice is issued on a taxable supply by a registered supplier and shows the tax separately, so the buyer can claim input credit. A bill of supply is issued where no tax is charged — exempt supplies, or a composition dealer — and must not show a tax amount. A proforma invoice is a quotation laid out like an invoice: not a tax document, no credit claimable, and it must stay out of your invoice series. A credit or debit note corrects an invoice already issued, referencing it. A receipt voucher covers an advance taken before a supply, and a refund voucher covers giving that advance back. A delivery challan moves goods where there is no supply.
If you can place the document you are about to issue in that list, you have avoided most of what goes wrong.
Booking invoices and money taken in advance
A booking is money received before the supply, which is a different thing in tax terms from money received for a supply, and the documents differ accordingly.
What is typically sent to confirm a booking is a proforma or a quotation — the lines, the price, the tax treatment, and what has to be paid to hold it. That is not a tax invoice and should not be numbered as one.
When the advance actually arrives, GST has a prescribed document for it: a receipt voucher recording the amount, the date, what it relates to and the tax position. If the booking is later cancelled and the advance returned, a refund voucher covers that. The tax invoice is raised when the supply happens, and the advance is shown as an amount already received against it rather than as a reduction of the taxable value.
Whether and when tax is payable on an advance has differed between goods and services and has been changed. If your trade runs on deposits — events, travel, custom manufacture — this is worth settling with your accountant once rather than deciding per booking.
Issuing these properly, free
- Tax invoices with the complete prescribed field set, tax split per line.
- Bills of supply for exempt and composition supplies, with no tax line.
- Proformas and quotations in their own series, converting to an invoice without retyping.
- Credit and debit notes that reference the original invoice rather than editing it.
- Separate consecutive series per document type, issued centrally so a number cannot repeat.
- Tax derived from the place of supply, so CGST/SGST against IGST is never a judgement call.
- A receivables position — what is unpaid, how old, and whose.
- Export of everything to CSV, Excel and JSON, on every plan.
- ₹0 on the free plan, no card, no expiry.
Issuing the right document, in order
- Decide what the transaction is: a taxable supply, an exempt supply, an offer, a correction, or money received in advance.
- Pick the document that matches it — a tax invoice, a bill of supply, a proforma, a credit or debit note, or a receipt voucher.
- Check your registration position. If you are not registered, or are under composition, a tax invoice showing tax is the wrong document.
- Use the series belonging to that document type, and let the number be issued rather than typed.
- Fill the mandatory content — including place of supply and HSN or SAC per line, which are the two most commonly omitted.
- Issue it within the time limit that applies to your type of supply.
- Keep it, and the records behind it, for the prescribed retention period.
Keeping the documents for as long as you have to
Invoices and the records behind them must be retained for a prescribed period counted from the due date of the annual return for that year, not from the date on the document — so the obligation runs considerably longer than most people assume. Check the period currently in force for your own case.
That has a practical consequence. A laptop, a phone and a folder of PDFs are not a retention plan, because the horizon outlasts most hardware and most staff. Where records are kept electronically they have to stay accessible and readable for the whole period, which means a format you can still open and a copy somewhere other than the machine that produced it.
It is also worth keeping them in a form that can be searched and totalled, not only read. When records are actually asked for, the request is rarely "send me invoice 412" — it is a period, a customer or a figure that has to be reconciled.
Dull, cheap to do, and expensive to reconstruct. Those three things together are why it is worth doing now rather than later.
The numbering series, which is where most of this goes wrong
The rule is short: a consecutive serial number, unique within the financial year, not more than sixteen characters, made only of letters, numbers, hyphens and slashes. One series, or clearly separated series where you genuinely need more than one — each consecutive in itself.
A file cannot enforce any part of that. The number is typed, which means it can be repeated, skipped, or quietly rolled back when yesterday's invoice is edited into today's. Nothing notices.
The half that is forgotten is cancellation. A cancelled invoice keeps its number and stays in the series as cancelled. Deleting the row and reusing the number leaves a gap in your books and a figure in your customer's, and reconciling those two is a long afternoon with a bad outcome.
Separate series per document type is the other discipline. Proformas, credit notes and bills of supply each need their own, and mixing them is how a tax invoice series ends up with holes in it.
What a GST invoice legally has to carry
Rule 46 of the CGST Rules sets out what a tax invoice must show, and it is a longer list than most invoice templates carry. Getting one field wrong does not usually cost you anything the day you raise it — it costs your customer their input credit months later, which is a harder conversation.
The fields are:
- Your name, address and GSTIN
- A consecutive invoice number, unique within the financial year
- The date of issue
- The customer's name, address and GSTIN where they are registered
- Place of supply, and the state code, for inter-state supplies
- HSN or SAC against every line
- Description, quantity, unit, rate and taxable value per line
- Rate and amount of CGST, SGST/UTGST, IGST and cess, shown separately
- Whether tax is payable on reverse charge
- Signature or digital signature of the supplier or an authorised person
Billixo fills these in from the customer and product records rather than asking you to remember them, which is the only reliable way a busy counter gets them all right every time.
CGST, SGST and IGST — worked out, not chosen
Whether a sale attracts CGST and SGST or IGST is not a preference. It follows from the place of supply: same state as your registration means the tax splits into central and state halves, a different state means one integrated tax at the combined rate.
That sounds simple and goes wrong constantly, because it is a dropdown in most billing software and a dropdown is something a tired person clicks past. In Billixo the split is derived from the state on the customer record against the state on your registration, and it changes the moment either does.
The consequence of getting it wrong is real: an IGST invoice raised as CGST/SGST has to be credited and reissued, and if the return has already gone in, amended.
The AI, and what it is actually for
The useful application of AI to billing is not a chatbot. It is the twenty minutes a day spent retyping things that already exist on paper.
- Scan a supplier bill. Photograph it; the lines, the GSTIN, the tax and the totals come back as a draft you check rather than a form you fill.
- Find the HSN code. Describe the product in plain words and get a code to confirm, instead of scrolling a list of eleven thousand.
- Ask about your own numbers. "What is outstanding over sixty days?" answered from your data, not a manual.
- Write the reminder. A polite, specific chase for an overdue invoice, ready to send on WhatsApp.
Nothing is sent anywhere until you ask for it, and the platform runs on whichever model it has been configured with — including one hosted on your own server.
Where this fits in a working day
Morning: yesterday’s supplier bills get photographed and become purchase records. Through the day: invoices go out as goods do, shared on WhatsApp before the customer has left. End of the week: the receivables list says who to call. End of the month: the GST summary is a download, not a project.
None of that requires a new habit, which is the point. A billing system that needs discipline to work is one that stops working the first busy week.
What "free" means here, exactly
The Free plan costs nothing, needs no card, and has no expiry date. It is not a trial that turns into a bill; it is a plan you can run a small business on indefinitely.
What it gives you:
- Real GST invoices with the full Rule 46 field set
- Customers and products, with HSN/SAC held against each
- A daily and monthly invoice allowance, generous enough for a small operation
- One login
- Export of your own data, whenever you want it
What it does not give you:
- A watermark-free PDF
- GSTR-1 and GSTR-3B export
- The AI features — bill scanning, HSN lookup, the assistant
- Extra team logins, bulk import, recurring invoices and reminders
Every new account also gets the full paid feature set for its first 14 days, so you can see what the ceiling looks like before deciding whether you need it. When that ends nothing is charged and nothing is deleted — the account simply settles onto Free.
Start free now — it takes an email address and about a minute.
Where your data lives
On the server this platform is installed on. Every record carries a company identifier and every query is scoped to the signed-in account at the framework level, so one business cannot read another’s data by any route, including a crafted one.
Sign-in is rate limited, sessions can be restricted to one device per user, and passwords are stored hashed. Exports are available on every plan, free included: if you ever want to leave, your data leaves with you.
Frequently asked questions
Is a VAT invoice still valid in India?
VAT was replaced by GST in July 2017, so for an Indian supply today the document is a GST tax invoice. VAT is still live in other countries, which is usually why the term comes up — if you are exporting, that obligation belongs to the buyer's jurisdiction, not on your invoice.
Can I issue one invoice for a whole day of small sales?
For small-value supplies to unregistered customers below a prescribed amount, where no invoice was asked for, a consolidated invoice for the day is permitted. It does not extend to B2B supplies, which are reported invoice by invoice because the customer's credit depends on the detail.
Does the free plan issue all of these?
The free plan issues complete tax invoices and bills of supply with every required field, at ₹0 with no card and no expiry. Quotations, credit notes, recurring invoices and the GSTR exports sit on the paid plans, and every new account gets the full set for its first fortnight.
Will my accountant be able to work with it?
That is what the GSTR-1 and GSTR-3B summaries are for. They export in formats a practitioner can open and reconcile without repairing the file first — which, in practice, is most of what a CA wants from a client’s billing software.
What happens to my data if I stop paying?
Nothing is deleted. The account settles back onto the Free plan: the paid conveniences switch off, the volume limits return, and every invoice, customer and product you created stays exactly where it is — including the export.
Try it — the demo is the product
There is no sales call and no scheduled demo, because a recorded walkthrough of somebody else’s data tells you nothing about your own. Open an account instead and raise a real invoice for a real customer; it takes about a minute and costs nothing.
Open the software demo → — sign in, or create a free account from the same screen.
See full details on the home page → — features, the AI, pricing and the answers to the usual questions.
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