A practical guide to e invoice system under gst — the flow from your billing system to the invoice registration portal and back, the fields that must be present, and what to do when one is rejected.
What changes on your invoice
The commercial content does not change. What is added is the IRN and the signed QR code, both of which have to be printed on the invoice given to the customer.
What does change is tolerance for incomplete data. An invoice missing an HSN, carrying a malformed GSTIN, or with a place of supply that contradicts the parties will simply be rejected. Software that let those through quietly before will now fail loudly.
That is, on balance, an improvement — the errors were always there, they were just discovered by the customer instead of by the portal.
The registration portal, and what it does
The Invoice Registration Portal is the government system that receives invoice data, validates it, assigns an Invoice Reference Number and returns a digitally signed invoice with a QR code. There is more than one such portal operated under the scheme, which is why the addresses people search for vary.
What goes to it is structured data in a prescribed schema, not a PDF of your invoice. What comes back is the IRN and the signed QR code, which then have to appear on the document you give the customer.
Taking data there is done either by uploading a file, through the portal's own tools, or through a provider that submits on your behalf from your billing software. That last route is what most businesses use, because manual upload for every invoice does not scale.
Two things worth knowing: the portal has offline utilities for bulk preparation, and it has downtime. What your process does when it is unavailable is a question to settle in advance, because billing cannot simply stop and an invoice issued without an IRN when one was required has to be dealt with afterwards.
We do not reproduce portal addresses or screen sequences here, because they change. Go to the official GST portal and follow its links rather than a third-party page, including this one.
What matters in your billing software
- Complete party masters — GSTIN and state on every registered customer, validated in format.
- HSN or SAC on every line, without exception.
- Place of supply derived, not chosen, so it can never contradict the parties.
- A clean, consecutive invoice series — duplicates are a rejection cause.
- Correct document types for credit and debit notes, referencing the original.
- Discipline about editing. A registered invoice cannot be altered; corrections are cancellation within the window or a credit note.
- Billixo enforces the first four by design, which is most of what the portal is checking.
The flow, step by step
- Confirm whether e-invoicing applies to you, based on the current turnover threshold.
- Complete your masters: GSTIN and state on parties, HSN or SAC on every item.
- Raise the invoice in your billing system as normal.
- The structured invoice is sent to the registration portal.
- The portal validates it and returns the IRN and a signed QR code.
- Print or share the invoice carrying the IRN and QR code.
- If it is rejected, read the reason before retrying — the usual causes are a missing HSN, an invalid GSTIN, a place-of-supply mismatch or a duplicate invoice number.
Cancellation, amendment and getting it wrong
A registered invoice cannot be edited. It can be cancelled within a limited window after registration, and after that the only route is a credit note referencing it.
That makes the check-before-you-register habit worth building. In practice it means reviewing the party, the place of supply and the totals on screen before generating, rather than after the customer queries it.
It also means your invoice numbering has to be right first time: a cancelled IRN does not release the invoice number for reuse.
If e-invoicing does not apply to you yet
Bill as though it might. The turnover threshold has only ever moved in one direction, and the work involved in being ready is work worth doing anyway: complete GSTINs, HSN on every line, place of supply derived rather than typed.
A business already billing that way flips a switch when the threshold reaches it. A business that is not spends a fortnight cleaning masters under a deadline.
The free plan produces invoices with all of those fields, which makes it a reasonable place to build the habit. Start free now.
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 e-invoice after generating it?
No. It can be cancelled within a limited window after registration; after that a credit note referencing the original is the only correction route.
Why do my e-invoices get rejected?
Overwhelmingly four causes: a missing HSN or SAC, a malformed or invalid GSTIN, a place of supply that contradicts the parties, or a duplicate invoice number. All four are master data problems rather than portal problems.
Does e-invoicing replace the e-way bill?
No, but the data flows across — details reported at registration can be used in e-way bill generation, so the same information is not entered twice.
Is it really free?
Yes. The Free plan is ₹0, needs no card and has no expiry. It has volume limits and leaves out the paid conveniences — watermark-free PDFs, GST return exports, the AI features, extra logins — but the invoices it produces are real GST invoices, and you can export your data from it whenever you like.
Do I need to install anything?
No. It runs in a browser, on a laptop, desktop or phone, so there is nothing to install, nothing to update and nothing tied to one machine. If the office computer dies, you sign in from another one and everything is there.
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.
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