GST prescribes several documents that look alike on paper and behave completely differently in law. Tax Invoice Bill is one of them. Here is what it does, what it must contain, and where it is commonly misused.
What every one of them has in common
Whichever document it is, three things apply. It needs a consecutive serial number unique within the financial year, of not more than sixteen characters and using only letters, numbers, hyphens and slashes. It needs identifying content for both parties. And it has to be retained for the prescribed period, which is counted from the due date of the annual return rather than from the date on the document.
Each document type also needs its own series. A proforma numbered in your tax invoice series is a genuine problem, because it consumes a number from a series that has to be consecutive and complete.
Rates, turnover thresholds, e-invoicing applicability and the time limits for issuing all change. Nothing on this page states one as a current fact — check the notification in force for your own circumstances.
The tax invoice: the document everything else is defined against
A tax invoice is what a registered supplier issues on a taxable supply. Its defining feature is that it shows the tax separately, line by line and head by head, which is what allows the recipient to claim input tax credit. That is its whole purpose: it is the instrument the credit chain runs on.
Which is why the fields are not negotiable. A combined "GST" figure instead of CGST and SGST shown separately, a missing place of supply, or no HSN against a line all make it deficient — and the person who suffers is usually your customer, whose claim does not stand up.
There is a time limit for issuing it and it differs between goods and services: for goods it is tied to the removal or delivery, for services to the completion of the supply. Check the limit applying to your type of supply rather than assuming the invoice can follow the payment at your convenience.
Two other things sit on top for some businesses. E-invoicing — reporting the invoice to the portal and getting an IRN back — applies above a turnover threshold that has been lowered repeatedly, so confirm whether it now applies to you. And an e-way bill may be needed for the movement of the goods, which is a separate document from the invoice.
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.
Setting up your document series
- Start free now — email and password, no card.
- Enter your business name, address and GSTIN once.
- Set the next number for your tax invoice series, carrying on from whatever you last issued.
- Give proformas and quotations their own prefix, so they can never consume an invoice number.
- Do the same for credit notes and for bills of supply if you make exempt supplies.
- Add your customers with their GSTINs, and your items with HSN or SAC codes and rates.
- Raise one of each document you actually use, and check the numbering behaved as you expected.
Timing: when the document has to exist
Issuing the right document late is its own problem, separate from issuing the wrong one. The time of supply decides when tax becomes payable, and the invoice date is one of the inputs to it — so an invoice raised whenever it is convenient can move a liability into a period you have already filed.
The limits differ by what is being supplied. For goods the trigger is tied to removal or delivery; for services it is tied to completion of the supply, within a prescribed number of days. Continuous supplies, supplies on approval and reverse-charge supplies each have their own rule.
The practical version of this is unglamorous: raise the invoice when the supply happens, not when the customer asks for it, and not in a batch at month end because that is when someone has time.
These limits have been amended before. Check the one applying to your type of supply rather than relying on a remembered number of days.
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.
Reverse charge, exports and the supplies that behave differently
Not every supply is a straightforward taxable sale. Some notified supplies put the tax liability on the recipient rather than the supplier. Exports and supplies to an SEZ can be made under a bond or LUT without payment of tax, or with tax and a refund claimed afterwards. Composition dealers cannot charge tax at all and must say so on the bill.
Each of these changes what the invoice has to say — the reverse charge marking, the LUT reference, the "composition taxable person" declaration. They are not exotic cases; most businesses hit at least one.
The fields are on the invoice in Billixo whether or not you use them, so the day you need one you are not looking for a workaround.
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.
Bill scanning, in practice
The single largest time cost in most small businesses is not raising invoices — it is entering purchases. A photograph of a supplier bill goes in and a structured draft comes out: supplier, GSTIN, line items, rates, tax split and total.
You check it. That is the workflow, and it is deliberate: an extraction you did not read is a liability, not a saving. But checking a filled form takes fifteen seconds and typing one takes three minutes, and that difference compounds over a month of purchases.
A note for accountants and CAs
If you are the person who has to make sense of a client’s billing at the end of the month, what you need from their software is narrow and specific: a complete outward supply summary, correct place-of-supply treatment, HSN present on every line, and an export you can open without repair.
Billixo produces GSTR-1 and GSTR-3B summaries and exports to CSV, Excel and JSON. Client-side, the invoice fields cannot be skipped, which removes the category of problem where the data was never captured in the first place.
Free, and what it costs you instead
Free software usually costs you something that is not money: your data held hostage, an export that does not work, ads inside your invoice, or a "free" tier so narrow it is a demo with a login screen.
The line here is drawn differently. Export works on the free plan — CSV, Excel and JSON — because data you cannot get out is not data you own. The invoice is a real compliant invoice, not a sample. The limits are on volume and on the conveniences, not on whether the thing works.
Start free now. If it does not suit you, take your data with you.
Reliability, backups and getting your data out
Cloud billing software is only as good as its worst day. Two things matter more than any feature list: that your data is backed up somewhere you can reach, and that you can export it in a format something else can read.
Exports here are CSV, Excel and JSON, on every plan including the free one, covering customers, products, invoices and payments. That is the honest test of whether software respects you — not what it promises, but what it lets you take when you leave.
Frequently asked questions
Can I edit an invoice after issuing it?
No. Once it has gone to the customer you issue a credit note or a debit note referencing the original. Editing the original leaves two versions of one invoice number in two sets of books, and the mismatch surfaces at reconciliation — usually in the following month.
Do I need a separate number series for each document type?
Yes, in practice. Each series has to be consecutive and complete within the financial year, so a proforma or a credit note that consumes a tax invoice number leaves a gap you then have to explain. Give each document type its own prefix.
What happens if I cancel an invoice?
The number stays with it and the invoice remains in the series marked as cancelled. It is not handed back for reuse — reusing it leaves a gap in your records and a figure in your customer's.
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.
Start free, decide later
You do not have to choose a plan to begin. Start on Free, use it for as long as it suits you, and upgrade only when a limit actually gets in your way — never automatically, and never because a countdown ran out.
Open the software demo → — or create the free account from the same page.
Read the full details → on the home page, including pricing and the AI features.
Related pages