E-Invoicing Software Requirements in India: A Compliance Guide

This guide is for business owners, accounts heads and IT managers in India whose turnover has crossed, or is about to cross, the e-invoicing threshold, and who need to make sure their billing or ERP software will cope. By the end you will understand how the e-invoicing system works, what the software must handle field by field, how it connects to your existing billing and ERP, where implementations usually fail, and what to put in your requirements checklist.

How e-invoicing works under GST

You still create invoices in your own software. What changes is that each B2B invoice must be reported to a government-authorised Invoice Registration Portal, usually called the IRP, before it is valid.

1. Your software creates the invoice in the prescribed JSON schema, with the seller, buyer, item, tax and value fields filled in the required format.
2. The JSON is sent to the IRP through an API, either directly from your software or through a GST Suvidha Provider or similar authorised intermediary.
3. The IRP validates the invoice against the schema and business rules, checks for duplicates, and generates a unique Invoice Reference Number, the IRN, which is a hash of your GSTIN, document type, document number and financial year.
4. The IRP digitally signs the invoice and returns the IRN, a signed QR code and the signed invoice data to your software.
5. Your software prints the invoice with the IRN and the QR code, and stores the signed response.
6. The data flows onward to the GST system for return auto-population and, when transport details are included, to the e-way bill system.

An invoice without a valid IRN is not a legal tax invoice for a business covered by e-invoicing, and the buyer's input tax credit depends on it appearing in their returns.

Who must comply with e-invoicing

Applicability is based on aggregate annual turnover at the PAN level in any financial year since the GST rollout. The threshold has been reduced in stages, bringing many mid-size manufacturers, traders and service businesses in Gujarat into scope. Check the current figure and effective date on the official e-invoice portal or with your CA rather than relying on any article.

• Covered documents: B2B invoices, exports, supplies to SEZ units, and credit and debit notes against those invoices.
• Not covered: B2C invoices to unregistered consumers, though a separate dynamic QR code requirement applies to large taxpayers for B2C invoices; bills of supply for exempt goods; delivery challans; and certain categories of businesses that are exempted by notification, such as some financial institutions, transport and passenger service operators, and SEZ units as sellers.
• Once in, always in: applicability is triggered by crossing the threshold in any past financial year, not just the current one.
• Reporting time limit: a rule now requires taxpayers above a certain turnover to report invoices to the IRP within a fixed number of days of the invoice date. The turnover level and the number of days have been revised, so confirm the current rule on the portal and build the deadline into your software as a configurable value.

If your turnover is close to the threshold, prepare now. Businesses that wait typically have three to four weeks to get software ready once a notification applies to them.

E-invoicing software requirements: what the software must handle

These are the functional requirements we build into billing and ERP systems for clients under e-invoicing. Each one is a place where an older system may fall short.

Schema fields and validation

The government schema has mandatory and optional sections: seller and buyer details with GSTIN, legal name, address and state code; document type and number; item lines with HSN code, quantity, unit, rate, taxable value, tax rates and amounts; document totals; and optional sections for dispatch, ship-to, payment, export and e-way bill details. The software must validate before sending: correct GSTIN format and status, HSN codes of the required length, state codes matching the GSTIN, totals that reconcile line by line and, for exports, currency and port details.

IRN generation and storage

The software must send the JSON, receive the IRN, acknowledgement number and date, the signed invoice and the signed QR code, and store all of them against the invoice permanently. It must never generate an IRN twice for the same document, and it must handle the IRP being slow or unavailable with a retry queue rather than a frozen screen.

Cancellation window

An IRN can be cancelled on the IRP only within a short window after generation, currently measured in hours; check the exact period on the portal. After that window the IRN cannot be cancelled, and a mistake must be corrected through a credit note or debit note. The software must therefore block edits to an invoice once its IRN exists, offer cancellation only within the window, record the cancellation reason, and prevent the same document number from being reused.

Credit notes and debit notes

Credit and debit notes against B2B invoices also need IRNs. The software must link each note to the original invoice, carry the correct document type code, and support common Gujarat scenarios such as rate difference notes on forging supplies and post-supply discounts for ceramic dealers.

B2B vs B2C handling

The software must decide automatically which invoices go to the IRP. A retailer in Rajkot selling to both registered dealers and walk-in customers needs the B2B invoice to fetch an IRN while the B2C invoice prints normally, with the dynamic QR code if that requirement applies to your turnover. Sending B2C invoices to the IRP gets them rejected, and skipping a B2B invoice makes it invalid.

E-way bill linkage

When goods move, the e-way bill can be generated in the same call as the IRN by including transporter and vehicle details. The software should let the dispatch team add transport details at invoicing or later, generate the e-way bill from the IRN, update vehicle numbers in transit, and print the e-way bill with the invoice. For manufacturers in Metoda GIDC sending daily consignments, this single step saves the most time.

Integrating e-invoicing with your billing and ERP

There are three ways to connect existing software to the IRP, and the right one depends on your volume and how old the system is.

Approach	How it works	Best for	Typical cost
Offline JSON upload	Software exports invoices as JSON; staff upload to the portal and key the IRN back in	Under 20 B2B invoices a day, temporary bridge	₹15,000 to ₹40,000 for the export tool
Direct API integration	Your billing or ERP calls the IRP API through an authorised route; IRN and QR return automatically	Any business with daily B2B invoicing	₹60,000 to ₹2 lakh depending on the system
Middleware or connector	A small service sits between an older desktop billing system or ERP and the IRP, reading invoices from the database and writing back the IRN	Legacy systems without an API layer	₹1 lakh to ₹3 lakh including database work

Whichever approach you choose, the integration must cover authentication and token renewal with the API provider, sandbox testing with test GSTINs before going live, error mapping so the accounts team sees "buyer GSTIN inactive" rather than a numeric code, an audit log of every request and response, and a reconciliation report comparing your invoice register with IRNs generated. If you run separate billing and accounting systems, the IRN must flow to both so returns and books match. Our accounting and GST billing software handles this as a built-in module rather than an add-on.

Common e-invoicing failures we see in Gujarat businesses

Most problems are data and process failures rather than portal failures.

• Inactive or wrong buyer GSTIN: the most common rejection. Fix by validating GSTINs at the time of adding a customer, not at invoicing.
• HSN code length: the required number of digits depends on turnover; short codes in the item master cause rejections across every invoice for that item.
• Rounding mismatches: line totals rounded differently from the document total. The schema has tolerance rules, but software that rounds per line and then again at the total often exceeds them.
• Editing after IRN: staff change the quantity on a printed invoice without realising the IRN is now wrong. Lock the document.
• Missing the cancellation window: an error noticed the next morning cannot be cancelled and needs a credit note, which the software may not support cleanly.
• Duplicate document numbers: two branches or two users generating the same invoice number in the same financial year. The IRP rejects the second.
• Token expiry and network drops: integrations that do not renew tokens or retry leave invoices stuck without IRNs, discovered only during return filing.
• Late reporting: invoices created but not sent to the IRP within the reporting time limit, usually because of a queue nobody monitors.

What JK Tech Hub has seen on e-invoicing projects

A forging unit in the Rajkot industrial belt crossed the threshold with a desktop billing system that had no API. Rather than replace it mid-year, we built a connector that read new invoices from its database, sent them to the IRP and wrote the IRN and QR back for printing. Setup took three weeks, most of it cleaning HSN codes and buyer GSTINs in the master data.

A ceramic manufacturer in Morbi with three dispatch points needed e-way bills generated with the IRN because trucks were waiting at the gate. Combining both in one step cut dispatch paperwork from about 15 minutes per consignment to under 3. E-way bill errors also fell, since transport details were entered once instead of twice.

A pharmaceutical distributor in Ahmedabad had the most trouble with credit notes. Expiry returns and rate differences produced dozens of notes a month, and the previous software created them as negative invoices. We rebuilt the note module to link each note to the original IRN and carry the right document type. Their reconciliation with returns went from a two-day exercise to a one-hour report.

E-invoicing software requirements checklist

Requirement	Why it matters	Ask the vendor
Full schema support with pre-send validation	Prevents IRP rejections	Which validations run before the API call?
Direct or intermediary IRP API integration	Automatic IRN and QR on every B2B invoice	Which route is used and who holds the credentials?
Signed response storage	Legal evidence and audit	Where is the signed invoice stored and for how long?
Invoice lock after IRN	Stops silent edits	Can a user change a document with an IRN?
Cancellation within the window with reason	Compliance with IRP rules	Is the window configurable when rules change?
Credit and debit notes with IRN and link to original	Corrections after the window	Show me a note against an e-invoice.
Automatic B2B vs B2C routing	Right invoices to the IRP only	How is the decision made per invoice?
E-way bill generation from the IRN	One step at dispatch	Can transport details be added later?
Retry queue and error mapping	No stuck invoices, readable errors	What happens when the IRP is down?
Reporting deadline monitoring	Avoids late reporting	Is there an alert for unreported invoices?
Reconciliation report	Invoice register vs IRNs vs returns	Can I export it for my CA?
Sandbox testing and go-live plan	Safe cutover	How many test invoices before live?

How to decide and what to do next

If your software already covers every row of the checklist, you are ready. If it covers most rows but has no API layer, a connector is the fastest and cheapest fix. If it fails on the fundamentals, such as locking invoices, linking credit notes or storing signed responses, it is time to replace the billing module rather than patch it, because each missing item becomes a compliance problem at scale.

Start with master data. Validate every customer GSTIN, fix HSN code lengths and confirm state codes before any integration work. That preparation usually takes longer than the software work and removes most rejections on day one.

Related reading and next step

• Accounting and GST billing software with built-in e-invoicing
• Manufacturing ERP with e-invoice and e-way bill at dispatch
• POS billing software for retailers with B2B and B2C invoicing
• How to choose the right ERP system for your business
• ERP software services in Rajkot

Share which billing or ERP system you use and your approximate daily invoice count, and we will reply with a fixed-price quote for e-invoicing integration within two working days through the contact page or on WhatsApp at +91 7265004040.