E-Invoicing Under GST — IRN, QR Code & 30-Day Rule Guide

Overview

There is a sentence every growing business hears sooner or later: your invoice is not an invoice until the government has seen it. That is e-invoicing in one line. If your aggregate turnover crossed ₹5 crore in any financial year since 2017-18, your B2B invoices, export invoices and credit/debit notes must be reported to the Invoice Registration Portal (IRP) and carry a unique Invoice Reference Number (IRN) with a digitally signed QR code. Without those two things, the document is not a valid tax invoice — your buyer cannot safely claim input tax credit on it, and you are exposed to penalty.

This is not "sending invoices by email". You still prepare invoices in your own billing software. The difference is one extra step: before the invoice goes to the buyer, its data goes to the IRP, which validates it and returns the IRN and QR code. The data then flows automatically into your GSTR-1 and into the e-way bill system. Done right, e-invoicing removes reconciliation work instead of adding it. Done late or wrong, it creates a class of problems — rejected documents, buyer ITC disputes, portal blocks — that did not exist before.

This page covers the whole subject the way it actually operates: who is covered, how the threshold is computed, the IRN/QR mechanics, the 30-day reporting rule, exemptions, the link to e-way bills, and what implementation looks like in a real accounting setup.

Is e-invoicing for you?

You are covered if:

• Your aggregate annual turnover (AATO) exceeded ₹5 crore in any financial year from 2017-18 onwards — computed across all your GSTINs under one PAN. Once crossed, the mandate continues even if turnover later falls below ₹5 crore.
• You make B2B supplies, export goods or services, supply to SEZ developers or units, make deemed-export supplies, or issue credit/debit notes against such supplies.

You are not covered if:

• Your turnover has never crossed ₹5 crore in any year since 2017-18.
• You deal only in B2C retail sales — consumer invoices do not need IRNs.
• You fall in a notified exempt category: SEZ units, insurers, banks and financial institutions (including NBFCs), goods transport agencies, passenger transport service providers, suppliers of admission to film exhibition in multiplexes, government departments and local authorities. [NEEDS VERIFICATION: confirm the current exemption list against the latest notification at publish.]

The trap: businesses approaching ₹5 crore often discover the threshold only when a large buyer asks for an IRN-bearing invoice. Check your AATO computation now, not at year-end.

The ₹5 crore threshold — the line, its history, and how it is computed

The threshold did not start at ₹5 crore. It walked down in six steps: ₹500 crore (1 October 2020), ₹100 crore (1 January 2021), ₹50 crore (1 April 2021), ₹20 crore (1 April 2022), ₹10 crore (1 October 2022), and finally ₹5 crore from 1 August 2023 via Notification 10/2023-Central Tax dated 10 May 2023. Each step pulled a new band of businesses into the system. If your turnover is between ₹5 and ₹10 crore, you are in the newest and largest cohort — and the cohort with the least institutional memory of how the system works.

Three computation rules decide whether you are in:

PAN-level aggregation. Aggregate turnover is counted across all GST registrations held under the same PAN — not per GSTIN, not per state. A business with ₹3 crore in Maharashtra and ₹2.5 crore in Gujarat is over the line.

Any year since 2017-18. The test looks back at every financial year from 2017-18 onwards. Cross ₹5 crore in 2019-20, drop to ₹3 crore every year after — you are still covered. There is no exit once you have entered.

Turnover, not profit. Aggregate turnover is the gross value of all taxable, exempt, export and inter-state supplies — before deducting taxes. Businesses with thin margins and high volumes cross this line much earlier than they expect.

If you are close to the line, compute it properly now. The cost of discovering you were covered — six months after the fact, with buyers questioning your invoices — is far higher than the cost of implementing early.

The IRN and the QR code — what the portal actually does

Here is the mechanics, without mystique. You prepare the invoice in your accounting or ERP software exactly as before. Your software (directly, or through a GST Suvidha Provider — a GSP) converts the invoice into the prescribed JSON schema and sends it to the IRP. The IRP validates the data — GSTINs, HSN codes, tax arithmetic, duplicate checks — and returns two things:

The Invoice Reference Number (IRN) — a unique 64-character hash computed from your GSTIN, the invoice number and the financial year. No two invoices can share one; the duplicate check is one of the portal's core validations.

The digitally signed QR code — containing the supplier and recipient GSTINs, invoice number and date, total invoice value, the IRN, and HSN summary data. [NEEDS VERIFICATION: confirm the exact QR payload fields at publish.] The signature is what makes the QR verifiable — anyone scanning it can confirm the invoice is genuinely registered.

Both must appear on the invoice you issue to the buyer. The IRP also pushes the invoice data into the GST system: it lands in your GSTR-1 and, where goods move, it pre-fills Part A of the e-way bill. One reporting action feeds three compliance outputs — that is the design working as intended.

What the IRP does not do: it does not store your invoice as the legal original, it does not replace your accounting software, and it does not validate the commercial terms of your deal. It validates structure and uniqueness, not business sense.

What must be decided before going live

Direct IRP vs GSP vs ERP-integrated. Small covered businesses can use the free IRP portal or offline tools. Businesses with volume need their ERP or billing software connected — directly to the IRP or through a GSP (GST Suvidha Provider). The GSP route is the common enterprise choice; the direct route suits businesses with in-house tech capacity.

Invoice numbering discipline. The IRN hashes your invoice number, so numbering must be unique per financial year per GSTIN and follow a consistent series. If your current numbering has gaps, duplicates across branches, or restarts mid-year, fix it before your first IRN — the portal will reject duplicates and your dispatch desk will stall.

Credit and debit note coverage. E-invoicing covers credit notes and debit notes too, not just tax invoices. Your returns process, sales-return workflow and rate-difference adjustments must all generate IRNs — the part of implementation most businesses forget until the first return lands.

B2B vs B2C separation. Only B2B documents need IRNs. If your billing mixes B2B and B2C in one flow, the system must classify correctly at the point of invoice creation — not as a month-end correction.

The 30-day question. If your AATO is ₹10 crore or more, you must report within 30 days of the invoice date (effective 1 April 2025 — see the dedicated section below). Your billing cycle must fit inside that window. Monthly-batch invoicing that runs 45 days late is structurally incompatible with this rule.

Advantages of a working e-invoicing setup

GSTR-1 practically writes itself

E-invoice data flows automatically into GSTR-1. The tables for B2B outward supplies populate from IRP data, which means the return your team files is built from the same data your invoices carry. Mismatches between books and returns — the classic audit trigger — shrink dramatically.

E-way bill Part A comes free

For goods movements, the IRP data flows to the e-way bill portal and Part A auto-populates. Your dispatch team fills only Part B (vehicle details). Two compliance steps collapse into one workflow.

Buyer disputes drop

When every invoice carries a verifiable IRN and signed QR, the "your invoice is not in our system" dispute largely disappears. Buyers can verify the document themselves, and their ITC claims rest on registered documents.

Duplicate and arithmetic errors get caught at source

The IRP validates HSN codes, GSTINs, tax calculations and duplicate invoice numbers before issuing the IRN. Errors that used to surface months later in reconciliations get rejected in seconds, at the point of creation.

E-invoice data strengthens your audit trail

A complete IRN trail is strong evidence of genuine supplies. In assessments and audits, the ability to show that every B2B invoice is portal-registered answers the genuineness question before it is asked.

It forces billing discipline that pays elsewhere

Unique invoice series, clean HSN masters, correct GSTIN capture, timely billing — e-invoicing forces all of these. Businesses consistently find their receivables, reconciliations and even working-capital cycles improve once billing discipline is systematised.

Future-proofing against threshold movement

The threshold has only ever moved down — ₹500 crore to ₹5 crore in under three years. A business at ₹4 crore today implementing e-invoicing voluntarily is simply early; a business at ₹6 crore scrambling after crossing is late. The direction of travel is clear.

Documents and inputs required

E-invoicing does not ask for "documents" the way a registration does — it asks for data discipline. What your implementation needs:

Master data:

• Clean GSTIN master for all customers (validated, with correct state codes)
• HSN/SAC master with correct codes for everything you sell
• Place-of-supply logic configured per transaction type

System inputs per invoice:

• Supplier and recipient GSTIN, addresses and state codes
• Invoice number (unique series), date, and type (regular, export, SEZ, deemed export)
• Line items with HSN/SAC, quantity, taxable value, tax rates and amounts
• Reverse-charge flag where applicable
• E-way bill linkage where goods move

Access and credentials:

• IRP login credentials with two-factor authentication (mandatory on the portals)
• GSP credentials if routing through a provider
• API credentials if integrating your ERP directly

E-invoicing implementation — step by step

Step 1 — Confirm coverage with a proper AATO computation

Compute aggregate turnover PAN-wise for every year from 2017-18. Include all GSTINs, all supply types. Document the working — if you are covered, this computation is the foundation; if you are close, it is your early-warning system.

Step 2 — Choose the integration route

Direct IRP portal for low volumes, GSP for managed connectivity, or ERP/API integration for high volumes. Decide based on invoice count, IT capacity and how your billing software handles JSON today.

Step 3 — Clean the masters

Validate every customer GSTIN, fix HSN/SAC codes, standardise invoice series per GSTIN per financial year, and configure B2B/B2C classification. Most implementation pain lives here, not in the portal.

Step 4 — Configure the JSON schema and test in sandbox

Map your invoice fields to the prescribed schema (FORM GST INV-01 particulars), generate test JSONs, and run them through the IRP sandbox. Fix every validation error before go-live — schema errors on day one mean invoices that cannot legally issue.

Step 5 — Set up users, 2FA and maker-checker

Create IRP users for the billing team, enable two-factor authentication, and decide who can generate, who can cancel (within 24 hours), and who reviews rejections. E-invoicing without access control is a fraud risk.

Step 6 — Go live with a parallel run

Run the new flow alongside the old for one billing cycle: generate IRNs, print QR codes, verify auto-population in GSTR-1 and e-way bill Part A. Confirm the buyer's copy carries both IRN and QR before you switch off the old process.

Step 7 — Build the 30-day and 24-hour watches

If you are in the ₹10 crore+ band, build a daily age-watch: no invoice older than 30 days unreported. For everyone, build a 24-hour cancellation watch: wrong IRNs must be caught and cancelled within a day, or corrected via credit note.

Step 8 — Reconcile monthly: IRP vs books vs GSTR-1

Every month, reconcile three numbers: invoices in your books, IRNs on the portal, and entries in GSTR-1. The three should agree. Investigate every gap — a gap is either a missed IRN (invalid invoice) or a data-flow failure, and both need fixing.

How long does it take?

| Activity | Typical time | |---|---| | AATO coverage computation | 1–3 days | | Master data cleanup (GSTIN/HSN/series) | 1–3 weeks (the long pole) | | GSP selection and contracting | 1–2 weeks | | ERP/API integration and sandbox testing | 2–6 weeks depending on the ERP | | Team training and parallel run | 2–4 weeks | | Full go-live | 6–12 weeks from decision for a mid-size business |

The portal itself is instant. The calendar time is master-data cleanup and integration — which is why starting before you cross the threshold beats starting after.

Fees

E-invoicing has no government fee — the IRP is free. Costs sit in integration and process.

| | Starter | Growth | Scale | |---|---|---|---| | Best for | Just crossed ₹5 crore; low invoice volume | ₹5–50 crore; regular B2B billing | ₹50 crore+; multi-GSTIN, high volume | | Coverage computation and applicability opinion | ✓ | ✓ | ✓ | | Master data cleanup (GSTIN/HSN/series) | ✓ | ✓ | ✓ | | GSP selection and onboarding | Assisted | ✓ | ✓ | | ERP/API integration | — | ✓ | ✓ | | 30-day reporting workflow design | — | ✓ | ✓ | | Team training + SOP | ✓ | ✓ | ✓ | | Monthly IRP–books–GSTR-1 reconciliation | — | ✓ | ✓ | | Multi-GSTIN rollout management | — | — | ✓ |

[NEEDS VERIFICATION: ComplyKart package pricing — confirm current fee bands before quoting.]

How ComplyKart helps

Consulting — We compute your AATO properly (PAN-wise, all years since 2017-18), give you a clear covered/not-covered/approaching opinion, and design the integration route that fits your volume and systems.

Documentation — Invoice-series redesign, HSN/SAC master cleanup, B2B/B2C classification rules, credit-note workflow documentation, and the 30-day and 24-hour watch procedures.

Filing — GSP onboarding, ERP/API integration support, sandbox testing, user setup with 2FA and maker-checker, and the parallel-run management through go-live.

Follow-up — Monthly three-way reconciliation (books vs IRP vs GSTR-1), 30-day age-watch for the ₹10 crore+ band, rejection triage, and buyer-ITC query support when a customer questions an invoice.

What we do not do — We do not choose your ERP or billing software for you (we integrate with what you have). We do not generate IRNs for invoices you have not shared with us. And we do not backdate-report documents the portal has already rejected — the 30-day wall is a system validation, not a discretion.

What happens after go-live

In the first 30 days — the billing team learns the new rhythm: invoice, JSON, IRN, QR, dispatch. Rejections cluster in week one (schema errors, duplicate numbers, bad GSTINs) and fall sharply once masters are clean. The first GSTR-1 auto-populated from IRP data is the moment the system proves its value.

In six months — e-invoicing is invisible infrastructure. GSTR-1 needs review rather than construction, e-way bill Part A arrives pre-filled, buyer invoice queries have dropped, and the monthly reconciliation takes hours instead of days.

Recurring compliance

• Every B2B invoice, export invoice and credit/debit note — report to the IRP and obtain the IRN before issuing to the buyer. No batching beyond the 30-day wall (₹10 crore+ band).
• 24-hour cancellation watch — wrong IRNs cancelled within a day; later errors corrected via credit notes.
• Monthly three-way reconciliation — books vs IRP vs GSTR-1.
• Annual AATO re-check — confirm your band each year (the 30-day rule follows the ₹10 crore line).
• User hygiene — 2FA, current mobile numbers, deactivated ex-employees.

The 30-day reporting rule — the deadline that rejects your invoice

This deserves its own section because it is the rule most likely to bite. The IRP does not merely advise prompt reporting — for covered taxpayers, it refuses late documents.

The history: from 1 November 2023, taxpayers with AATO of ₹100 crore or more could not report documents older than 30 days. Then, via GSTN advisory dated 5 November 2024, the threshold was lowered: from 1 April 2025, taxpayers with AATO of ₹10 crore or more cannot report e-invoices, credit notes or debit notes older than 30 days from the document date. The portal validation simply disallows it — an invoice dated 1 April 2025 cannot be reported after 30 April 2025.

Below ₹10 crore AATO, there is currently no portal-enforced window — but the invoice still needs its IRN before it counts as a valid tax invoice, so "report at invoicing time, before GSTR-1" remains the working rule.

Practical consequences:

• Billing cycles must fit inside 30 days. If your sales team finalises invoices 45 days after the month ends, your process is structurally non-compliant. Redesign the cycle, not the rule.
• There is no condonation. A missed window means the document cannot get an IRN through the normal route. You are left with credit-note corrections and difficult conversations with the buyer about ITC.
• Credit and debit notes are covered too. The 30-day wall applies to all document types needing IRNs — a rate-difference credit note raised two months late hits the same wall.

Cancellation, amendments and credit notes

Cancellation — an e-invoice can be cancelled on the IRP within 24 hours of IRN generation. Partial cancellation is not possible; it is all or nothing. After 24 hours, the IRN stands permanently.

Amendment — there is no "edit" on the IRP. A wrong invoice that survives past 24 hours is corrected the GST way: issue a credit note (also IRN-bearing, also within the 30-day wall if you are in that band) and reflect the correction in GSTR-1.

The ITC consequence chain — Rule 48(5) provides that an invoice not issued in the prescribed e-invoicing manner is not treated as an invoice for Section 31 purposes. Since Section 16 makes possession of a tax invoice a condition for input tax credit, your buyer's ITC claim on a non-IRN invoice is vulnerable — which is why large buyers now reject invoices without IRNs at goods receipt.

E-invoicing vs e-way bill — how the two systems talk

| | E-invoicing (IRN) | E-way bill (EWB-01) | |---|---|---| | Legal home | Rule 48(4), CGST Rules | Rule 138, CGST Rules | | Trigger | Turnover-based (AATO >₹5 crore) | Movement-based (consignment >₹50,000) | | Applies to | B2B, exports, SEZ, deemed exports, credit/debit notes | Movement of goods by any mode | | B2C | Not covered | Covered (bill needed above ₹50,000) | | Output | IRN + signed QR on the invoice | EWB number for the journey | | Data flow | IRP → GSTR-1 and → e-way bill Part A | Standalone per movement |

The practical relationship: e-invoicing feeds the e-way bill, not the other way round. When the IRP issues your IRN, invoice data flows to the e-way bill portal and Part A pre-fills. You add Part B. But the systems are independent obligations — a business under e-invoicing still needs e-way bills for B2C movements above ₹50,000 (no IRN exists, so Part A is manual), and a business below the e-invoicing threshold still needs e-way bills for every qualifying movement.

Penalties

The penalty position has two layers, and one of them needs care at publish:

• Invalid-invoice consequence (certain): an invoice without the prescribed IRN is not treated as a tax invoice (Rule 48(5) read with Section 31). The buyer's ITC on it is exposed, and the document fails the Section 16 "tax invoice" condition.
• Monetary penalty (verify exact provision): practitioner sources cite ₹50,000 per document (split between CGST and SGST) for issuing invoices without IRNs, while others reference ₹10,000 per invoice under Section 122. [NEEDS VERIFICATION: confirm the applicable penalty provision and quantum against the bare Act at publish.]
• 30-day wall (systemic): for the ₹10 crore+ band, late documents are rejected by the portal — the "penalty" is operational, not monetary, and often worse.

Common mistakes businesses make

Discovering coverage late. The AATO test looks back to 2017-18. Businesses compute it for the first time when a buyer demands an IRN — and find they have been non-compliant for months.

Dirty masters. Invalid customer GSTINs, wrong HSN codes and duplicate invoice series cause most IRP rejections. The portal is unforgiving; cleanup is the real project.

Forgetting credit notes. The sales team implements e-invoicing; the accounts team keeps issuing manual credit notes. Both need IRNs.

B2B/B2C misclassification. One billing flow, mixed customers, no classification logic — B2B invoices go out without IRNs because the system treated them as retail.

Monthly-batch billing vs the 30-day wall. A billing cycle longer than 30 days is incompatible with the ₹10 crore+ reporting rule. The cycle must change.

Cancelling after 24 hours. There is no late cancellation. Teams that discover errors on day three must use credit notes — and need a documented process for it.

Assuming e-invoicing replaces e-way bills. It does not. B2C movements above ₹50,000 still need e-way bills with manually filled Part A.

FAQs

1. Is e-invoicing mandatory for a business with ₹5 crore turnover?

Yes, if aggregate turnover exceeded ₹5 crore in any financial year from 2017-18 onwards (counted across all GSTINs on the PAN). The mandate has applied since 1 August 2023. If turnover merely touched ₹5 crore without exceeding it, the current notification's "more than ₹5 crore" test needs careful reading — get an applicability opinion. [NEEDS VERIFICATION: confirm "exceeds" vs "exceeds or equals" framing at publish.]

2. What exactly is an IRN?

The Invoice Reference Number — a unique 64-character hash the IRP generates from your GSTIN, invoice number and financial year. It is the proof that your invoice is registered with the government, and it must appear on the invoice along with the signed QR code.

3. Does e-invoicing apply to B2C sales?

No. Retail invoices to unregistered consumers do not need IRNs. But remember: B2C movements of goods above ₹50,000 still need e-way bills.

4. What is the 30-day rule?

Taxpayers with AATO of ₹10 crore or more must report invoices, credit notes and debit notes to the IRP within 30 days of the document date, effective 1 April 2025. The portal rejects older documents. Below ₹10 crore there is currently no portal-enforced window.

5. Can I cancel a wrong e-invoice?

Within 24 hours of IRN generation, yes — full cancellation only, on the IRP. After that, correct through a credit note (which itself needs an IRN).

6. What happens if I issue an invoice without an IRN?

The document is not a valid tax invoice (Rule 48(5)), your buyer's ITC claim on it is vulnerable, and monetary penalty applies per document. [NEEDS VERIFICATION: confirm penalty provision and quantum at publish.]

7. Who is exempt from e-invoicing?

SEZ units, insurers, banks and financial institutions including NBFCs, goods transport agencies, passenger transport services, multiplex film exhibitors, government departments and local authorities — even above the turnover threshold.

8. How is aggregate turnover computed for the threshold?

PAN-wise, across all your GSTINs, for each financial year from 2017-18. It includes taxable, exempt, export and inter-state supplies — gross values, not profits.

9. Once covered, can I exit if turnover falls?

No. Crossing the threshold in any year since 2017-18 brings you in permanently under the current framework. There is no exit provision.

10. Do credit notes and debit notes need IRNs?

Yes — where they relate to covered supplies. This is the most commonly missed part of implementation.

11. What is a GSP?

A GST Suvidha Provider — an authorised intermediary that connects your billing software to the IRP. Most mid-size businesses route e-invoicing through a GSP rather than integrating directly.

12. Is the IRP the same as the GST portal?

No. The IRP (Invoice Registration Portal, einvoice.gst.gov.in) handles invoice registration and IRNs; the GST portal (gst.gov.in) handles returns and registration. They are linked — IRP data flows into GSTR-1 — but they are separate systems with separate logins.

13. What data does the signed QR code contain?

Supplier and recipient GSTINs, invoice number and date, total invoice value, the IRN, and HSN summary data — digitally signed so anyone can verify authenticity. [NEEDS VERIFICATION: confirm exact QR payload fields at publish.]

14. How does e-invoicing affect GSTR-1?

E-invoice data auto-populates the B2B tables of GSTR-1. You review rather than build the return — but you remain responsible for its correctness, so the monthly reconciliation still matters.

15. How does e-invoicing connect to e-way bills?

IRP data flows to the e-way bill portal and pre-fills Part A. You (or your transporter) still fill Part B with vehicle details. For B2C movements, Part A must be filled manually since no e-invoice exists.

16. Is 2FA required on the e-invoice portal?

Yes — two-factor authentication is the operating norm on the e-invoice and e-way bill portals. Keep registered mobile numbers current for all users.

17. What if the IRP portal is down when I need to dispatch?

Portal outages are rare but real. Have a documented contingency: hold dispatch where possible, and never move goods on the assumption that "the portal was down" excuses a missing e-way bill — it does not, as a matter of course. Courts have occasionally accepted genuine technical glitches as mitigation, but it is exception, not policy.

18. Do exports need e-invoices?

Yes — export invoices (with or without payment of tax) by covered taxpayers need IRNs, as do supplies to SEZ developers and units and deemed exports.

19. Can I implement e-invoicing voluntarily below ₹5 crore?

Yes, and businesses approaching the threshold often do — it front-loads the master-data cleanup and integration work, and the GSTR-1 and e-way bill automation benefits apply regardless of mandate.

20. What should I do first if I just discovered I was covered?

Stop issuing non-IRN B2B invoices immediately, compute the exact coverage start date, implement on priority, and take advice on the historical gap — voluntary disclosure and correction beats discovery in assessment. Do not backdate documents to manufacture compliance.

Sources

• CGST Act, 2017: Section 2(6) (aggregate turnover), Section 16 (ITC conditions), Section 31 (tax invoice)
• CGST Rules, 2017: Rule 46 (invoice particulars), Rule 48(4) (e-invoicing manner), Rule 48(5) (consequence of non-compliant invoice); Form GST INV-01
• Notification 13/2020-Central Tax (e-invoicing framework) as amended; Notification 10/2023-Central Tax dated 10.5.2023 (threshold lowered to ₹5 crore w.e.f. 1.8.2023)
• GSTN advisories: 13.9.2023 (30-day rule for AATO ≥₹100 crore from 1.11.2023); 5.11.2024 (threshold lowered to AATO ≥₹10 crore w.e.f. 1.4.2025)
• Secondary: taxguru.in, cleartax.in, taxmann.com, nwayerp.com practitioner guides (cross-checked against notifications; penalty quantum and QR payload marked for verification)

This page is reviewed against the CGST Act/Rules, CBIC notifications and GSTN advisories. [NEEDS VERIFICATION items: penalty provision and quantum for non-IRN invoices; exact QR code payload fields; "exceeds ₹5 crore" vs "₹5 crore or more" framing; current exemption list; ComplyKart fee bands.]

Schema markup plan

Service + FAQPage (20 Q&As) + HowTo (8 implementation steps) + BreadcrumbList + GovernmentService (IRP). HowTo steps carry realistic durations; FAQPage answers stay under 400 characters each in implementation.