A practical guide to e invoice1 — 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.
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.
HSN and SAC codes, and how many digits you need
Every line on a tax invoice needs an HSN code for goods or a SAC for services. How many digits depends on your aggregate turnover in the preceding financial year — smaller businesses report fewer digits than larger ones, and B2B and B2C invoices are treated differently.
Because the requirement is tied to turnover and has been tightened in stages, the practical answer is to store the fullest code you can against each product once, and let the software report at the level required. A six-digit code can always be truncated; a two-digit one cannot be expanded.
Billixo keeps the code on the product record and carries it onto every line automatically, and its AI HSN lookup will suggest one from a plain description when you genuinely do not know.
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.
The price, plainly
Free is ₹0 and stays ₹0. The paid plans are bought for a fixed term, paid once, with no auto-renewal and no card kept on file — when a term ends the account drops back to Free until you decide to buy again.
There is no per-invoice charge, no per-user surprise on the free plan, and no feature that is technically included but practically throttled. What the plan says you get is what you get.
Compare the plans on the home page, or just start free now and look at the ceiling from the inside.
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
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.
Do I need e-invoicing to use Billixo?
No. Billixo produces fully compliant GST invoices whether or not e-invoicing applies to you, with the complete field set the registration portal checks for.
Who does e-invoicing apply to?
It applies above an aggregate turnover threshold that has been lowered in stages since introduction. Because it has changed more than once, check the current notification or the portal rather than relying on any article for the figure.
Are the invoices valid for GST?
Yes. Every invoice carries the fields Rule 46 requires — GSTIN, HSN/SAC on each line, place of supply, the correct CGST/SGST or IGST split, and a consecutive invoice series that restarts each financial year.
Can I move my existing customers and products in?
Yes. Bulk import from CSV or Excel on any paid plan, and export back out in CSV, Excel or JSON at any time, including on Free. Most people bring their party and item lists across in one pass and carry outstanding invoices as opening balances.
See it working on your own bills
The fastest way to judge billing software is to bill with it. Photograph one supplier invoice, raise one sales invoice, and look at the PDF your customer would receive.
Open the software demo → — free account, no card, about a minute to set up.
More details on the home page → — what it does, what it costs, and where the limits are.
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