How to Choose an E-Invoicing Provider in India: GSP vs ASP vs ERP-Native (2026)
Choose an e-invoicing provider by deciding first where your invoice is born and who will call the IRP. Every e-invoice in India is registered on a government-notified Invoice Registration Portal (IRP), which validates it and returns the IRN and signed QR code. What you are really choosing is the route to the IRP: the free portal and offline tools, your ERP's built-in e-invoicing, a GSP-backed compliance platform, an application (ASP) that generates the IRN inside its own workflow, or a direct API integration with an IRP.
Three facts usually settle it: the system that creates the invoice, your monthly invoice volume across GSTINs, and your turnover, which decides whether some IRPs will even offer you direct API access. Use the route comparison and the ten-point checklist below to shortlist, the scoring table to compare vendors, and the red flags and questions to test them. This is operational guidance, not tax advice: confirm applicability with your tax advisor and the GSTN and NIC portals.
Key Takeaways
- The IRP registers the invoice; your provider prepares, validates and submits it. Choosing an IRP and choosing software are separate decisions.
- There are six IRPs. Per GSTN’s published API details (as on 29 Nov 2023), direct API access on the NIC and Cygnet IRPs needs turnover of ₹100 crore or more; IRIS and Clear are open to all e-invoicing-enabled taxpayers.
- Core e-invoice APIs are free on the IRPs. Paid software is paying for validation, integration, bulk handling, failover and support.
- From 1 April 2025, businesses with AATO of ₹10 crore and above must report e-invoices within 30 days of the document date.
- Generate the IRN where the invoice is born, or make sure it is written back there automatically.
How we evaluated
Rules and IRP details in this guide come from GSTN, NIC and CBIC documents listed in the sources at the end, reviewed in October 2026. Where a document carries an "as on" date, we say so, because IRP onboarding terms change. The checklist reflects what breaks in day-to-day invoicing for multi-GSTIN consumer brands: rejected payloads, IRNs that never reach the ERP, e-way bills typed twice and documents that age out of the reporting window. It compares routes and capabilities, not named vendors; for a vendor landscape, see our top 10 e-invoicing solutions in India.
Disclosure: FilFlo publishes this guide and sells software in this category; it appears in one labelled section. This is operational guidance, not tax advice.
The Moving Parts: IRP, GSP, ASP, ERP-Native and Direct API
IRP (Invoice Registration Portal). The registrar. You submit invoice data in the notified schema; the IRP validates it and returns the IRN, acknowledgement number and a signed invoice with QR code. Per NIC, IRNs are needed for invoices, credit notes and debit notes on B2B and export supplies. GSTN's master site, einvoice.gst.gov.in, lets you check whether your GSTIN is enabled.
GSP (GST Suvidha Provider). An intermediary authorised by GSTN to connect software to the GST systems through APIs. On the NIC IRP, you create an API user against the GSP you use, and NIC notes you can register with more than one GSP for IRN generation. The NIC portal lists registered GSPs and ERPs.
ASP (Application Service Provider). The application your team actually uses: a billing tool, compliance dashboard, distribution system or order-operations platform. An ASP reaches the government systems through a GSP; many vendors are both.
ERP-native. NIC recognises integration through registered ERPs as its own route. In practice, ERP-native means your ERP or accounting software calls the IRP from the invoice screen, directly as a registered ERP or through a GSP it partners with.
Direct API. Your own system calls the IRP. On NIC this means sandbox testing, submitting a test summary report, IP whitelisting and receiving a client ID and secret; companies under the same PAN can share credentials. You own monitoring, retries and every schema change.
The Six IRPs and Who Gets Direct API Access
GSTN lists six IRP portals. Four are operated by private companies, several of which also sell e-invoicing software, so keep the two decisions apart: which IRP registers your invoices, and which software prepares them. The eligibility column below is from GSTN's "API Details of all 6 IRPs" sheet, dated as on 29 November 2023; confirm current terms on each IRP before planning a direct integration.
| IRP | Operator | Portal | Direct API eligibility (GSTN, as on 29 Nov 2023) |
|---|---|---|---|
| NIC-IRP 1 | NIC | einvoice1.gst.gov.in | Direct API option only at turnover of ₹100 Cr or more |
| NIC-IRP 2 | NIC | einvoice2.gst.gov.in | Direct API option only at turnover of ₹100 Cr or more |
| Cygnet IRP | Cygnet | einvoice3.gst.gov.in | Direct API option only at turnover of ₹100 Cr or more |
| Clear IRP | Clear | einvoice4.gst.gov.in | All e-invoicing-enabled taxpayers can access its APIs |
| EY IRP | EY | einvoice5.gst.gov.in | Turnover verified at direct API user creation in sandbox |
| IRIS IRP | IRIS | einvoice6.gst.gov.in | Open to direct integration for e-invoicing-enabled B2B and SEZ taxpayers |
The same GSTN sheet notes that the core e-invoice APIs are free of cost on every IRP. In a January 2025 advisory, GSTN added that NIC-IRP 1 and 2 are interoperable and that the other IRPs can be used if NIC is down, which is why failover belongs on your checklist.
Five Routes to the IRP, Compared
| Route | How it works | Best for | Watch out for |
|---|---|---|---|
| Portal and offline tools | Prepare invoices in NIC’s offline tools, upload the file to the IRP portal and download the IRN and signed QR. | Low volumes, a single GSTIN, no ERP integration | Manual effort, re-keying, no validation before upload, IRN stored outside your books |
| ERP or accounting software with built-in e-invoicing | Your ERP (as a registered ERP or through its GSP partner) calls the IRP from the invoice screen. | One ERP where invoices are born, moderate volume | Depth of validation, bulk handling and IRP failover vary by product and edition |
| GSP-backed compliance platform | A compliance vendor that is a GSP takes invoice data from your systems, validates it and calls the IRP. | Several ERPs or GSTINs, high volume, central tax team | One more integration to maintain; IRN must be written back to the source system |
| ASP or workflow application on a GSP | An application (billing, order operations, distribution) generates the IRN inside its own workflow through a GSP or IRP connection. | Invoices born in an operations workflow, not in the ERP | Confirm who the GSP is, and that the ERP still receives the IRN and QR |
| Direct IRP API | Your own system calls an IRP API with your credentials after sandbox testing and IP whitelisting. | Large taxpayers with an engineering team and strict data-control needs | Eligibility varies by IRP; you own monitoring, retries, schema changes and support |
The Decision Checklist: 10 Criteria
- Where is the invoice born? In the ERP, in an accounting tool, in a distribution or order-operations workflow, or in spreadsheets. The IRN should be generated where the invoice is created, or written back there automatically.
- Applicability and reporting window. Your AATO decides whether e-invoicing applies and whether the 30-day reporting limit applies. The provider should track document age and warn before the window closes.
- Route to the IRP. GSP, registered ERP, ASP on a GSP, or direct API. Know which one each vendor uses, which IRP it registers on, and whether it can switch IRP during an outage.
- Validation before submission. GSTIN status, HSN, state and pincode codes, tax rates, document numbering and duplicate checks should run before the IRP call, with readable errors per invoice.
- Multi-GSTIN and invoice series. Separate credentials, series and users per GSTIN, without separate logins or duplicate masters for each registration.
- E-way bill linkage. The IRP allows generating the e-way bill along with the IRN or later from it. Check how transporter and vehicle details are captured and whether e-way bills stay linked to the invoice.
- Credit notes, debit notes and cancellations. IRNs are needed for credit and debit notes too. IRN cancellation is allowed within 24 hours of generation and not while an active e-way bill exists, so cancellation must be fast and visible.
- Storage, print and write-back. IRN, acknowledgement number, signed JSON and QR stored against each invoice, printed on your template, and pushed back to the ERP so nobody copies them by hand.
- Access and credential security. Role-based access, API users per GSTIN, no shared portal passwords, and an audit trail of who generated or cancelled what.
- Commercials and support. Pricing basis (per IRN, per GSTIN, per user, per API call), month-end support hours, and how schema or rule changes are rolled out.
Scoring Table You Can Copy
Score 1 to 5 per row after a sandbox demo on your own invoices, multiply by the weight, total the rows and divide by 5 for a score out of 100. If you have a single GSTIN, move the multi-GSTIN weight to validation; if you are below the 30-day rule threshold, move that weight to ERP write-back.
| Criterion | Weight | What a 5 looks like | What a 1 looks like | Score (1-5) |
|---|---|---|---|---|
| Fit with where invoices are born | 15 | IRN generated in the source system or written back automatically | Separate tool, IRN copied back by hand | |
| Validation before IRP call | 15 | Rule checks with per-invoice, readable errors | Raw IRP error codes only | |
| IRP route and failover | 10 | Can switch IRP during an outage; retries queued | "The portal never goes down" | |
| 30-day window control | 10 | Ageing alerts by GSTIN before the cut-off | No tracking of document age | |
| Multi-GSTIN and series | 10 | One master, many GSTINs, clean series | One login and setup per GSTIN | |
| E-way bill linkage | 10 | E-way bill with or from IRN, linked to invoice | Separate module with re-keying | |
| Credit notes and cancellations | 10 | Notes and cancellations in the same flow, with alerts | Handled on the portal manually | |
| Storage, print and ERP write-back | 10 | IRN, ack and QR stored and pushed to ERP | Downloads saved in folders | |
| Security and audit trail | 5 | Roles, API users, logs | Shared credentials | |
| Commercials and support | 5 | Clear pricing basis, month-end support | Per-retry charges, ticket-only support |
Weights total 100. Weighted score = sum of (weight × score) ÷ 5. Anything not shown working in the sandbox scores 1.
Red Flags to Watch for in Demos
- The vendor will not trigger a validation error live in the sandbox (an invalid GSTIN or a duplicate document number) to show you what your team will see.
- The answer to "what happens when the IRP is unavailable" is an uptime figure rather than a queue, retry and failover process.
- "Bulk upload" means download an Excel, fix it offline and upload again, with no row-level error report.
- IRN and QR are generated but not written back to your ERP invoice, so someone copies them across.
- No view of documents approaching the 30-day reporting limit, if you are at or above the ₹10 crore AATO threshold.
- Portal credentials collected over email or shared across users instead of API users and roles.
- E-way bills shown as a separate product where vehicle and transporter details are typed again.
Questions to Ask Every Vendor
- Are you a GSP, an ASP working through a GSP (which one), an IRP operator, or a feature inside an ERP?
- Which IRP do you register our invoices on, and can you switch to another IRP during an outage?
- Which validations run before the IRP call, and how are errors shown per invoice?
- How do you track the 30-day reporting window by GSTIN?
- How are the IRN, acknowledgement number, signed JSON and QR stored and written back to our ERP?
- How do you generate e-way bills from an IRN, and how do you handle Part B updates?
- How do you handle a cancellation request after 24 hours, or when an e-way bill is active?
- How are API users and credentials managed per GSTIN, and who in our team can cancel an IRN?
- What is the pricing basis, and are retries or failed calls charged?
- How quickly are IRP schema and rule changes rolled out, and are we notified in advance?
- Can we export all IRNs and signed documents if we leave?
If your shortlist is mostly compliance platforms, our ClearTax alternatives guide compares them on route, ERP connectors and fit.
Invoices Born as Channel POs?
If your invoices start life as quick commerce, modern trade or distributor purchase orders, see IRN, e-way bill and GRN handled in the same order flow.
Where FilFlo Fits
FilFlo is not a GSP and not a standalone e-invoicing utility. FilFlo is the order-to-cash operations layer for FMCG brands selling through quick commerce, plus modern trade, general trade distributors and institutional buyers. In the route table above, it sits in the "application generates the IRN inside its own workflow" row: when an order reaches invoicing, FilFlo builds the e-invoice, obtains the IRN and stores the IRN, acknowledgement number and signed QR code against the order, alongside the e-way bill, multi-GSTIN invoicing profiles and invoice series.
On the ERP side, Microsoft Dynamics 365 is a live native API (OData, bidirectional): approved orders go out and invoices raised in Dynamics 365 are read back, so the IRN lives where the invoice was born. Tally and Zoho Books receive export formats rather than a connector. FilFlo also closes the GRN gap and manages credit notes against platform settlements today; deduction classification and payment reconciliation are on the roadmap.
Not the right fit if: your invoices are created in an ERP and you only need bulk IRN generation, validation and failover at volume. A compliance platform or your ERP's built-in e-invoicing is the better buy there. Pricing is quote-based.
Frequently Asked Questions
What is the difference between a GSP and an ASP for e-invoicing?
A GSP (GST Suvidha Provider) is an intermediary authorised by GSTN to connect software to the GST systems through APIs; NIC lists the GSPs registered for e-invoicing on its portal. An ASP (Application Service Provider) builds the application your team uses, such as a billing tool or compliance dashboard, and reaches the government systems through a GSP. Many vendors are both. What matters for you is who builds and validates the invoice payload, who calls the IRP, and who supports you when a call fails.
Can my business connect directly to an IRP API without a GSP?
Possibly, depending on the IRP and your turnover. GSTN’s published API details for the six IRPs (as on 29 November 2023) say the two NIC IRPs and Cygnet offer a direct API option only to taxpayers with turnover of ₹100 crore or more, IRIS and Clear open direct integration to all e-invoicing-enabled taxpayers, and EY verifies turnover when a direct API user is created. Direct integration also means sandbox testing, IP whitelisting and credential management on your side. Confirm current terms on each IRP’s onboarding page.
Is e-invoicing mandatory for my business in 2026?
Under Notification 10/2023-Central Tax, e-invoicing applies from 1 August 2023 to registered persons whose aggregate turnover exceeded ₹5 crore in any financial year from 2017-18, with certain categories exempt. We found no later change to that threshold at the time of writing. Check your GSTIN on the e-invoice enablement search at einvoice.gst.gov.in and confirm with your tax advisor; this is operational guidance, not tax advice.
What is the 30-day e-invoice reporting limit?
From 1 April 2025, taxpayers with AATO of ₹10 crore and above cannot report an e-invoice on the IRP more than 30 days after the document date. GSTN’s advisory of 5 November 2024 says it applies to invoices, credit notes and debit notes. Your provider should warn you before a document ages out, not after the IRP rejects it.
What makes an e-invoicing solution enterprise-grade in India?
Six capabilities: intake from several ERPs or billing systems, validation before the IRP call, failover to another IRP during an outage, ageing alerts for the 30-day reporting window, clean multi-GSTIN and invoice-series management, and a full audit trail with role-based access. Volume alone does not make a tool enterprise-grade; test these six in a sandbox on your own invoices.
Do we need separate e-invoicing software if our ERP already supports it?
Often not. If your ERP produces correct invoices and generates the IRN from the same screen, a separate tool adds a hand-off. A separate platform earns its place with several ERPs or GSTINs, high-volume validation, IRP failover needs, or invoices born in an operations workflow.
Is there a free e-invoice preparation utility?
Yes. The NIC portal supports bulk IRN generation from a file prepared with its bulk generation tools (under Help, Tools). NIC also released an offline Excel-based tool, GePP, for small taxpayers to prepare e-invoice JSON and print invoices with the QR code; check its current availability on the portal. These suit low volumes. GSTN also notes that the core e-invoice APIs are free on the IRPs, so paid software is paying for preparation, validation, integration and support.
Sources
- GSTN, "E-Invoice Portal: API Details of all 6 IRPs (As on 29th Nov 2023)": https://tutorial.gst.gov.in/downloads/news/e-invoice_api_integration_guide_irps.pdf
- NIC, "E-Invoice System" process note (IRN generation modes, API registration): https://einvoice1.gst.gov.in/Documents/eInvoice_process.pdf
- NIC e-invoice API sandbox, Cancel IRN (24-hour window, active e-way bill condition): https://einv-apisandbox.nic.in/version1.03/cancel-irn.html
- GSTN advisory, 5 November 2024, time limit for reporting e-invoices (AATO ₹10 crore and above, from 1 April 2025), copy published by Maharashtra GST: https://www.mahagst.gov.in/public/uploads/gstnadvisory/1760531580_293%20Advisory%20Time%20Limit%20for%20Reporting%20e%20Invoice%20on%20the%20IRP%20Portal%20%20Lowering%20of%20Threshold%20to%20AATO%2010%20Crores%20and%20Above.pdf
- GSTN advisory, 24 January 2025, business continuity for e-invoice and e-way bill systems (IRP interoperability and fallback), as reproduced at: https://taxo.online/latest-news/25-01-2025-gstn-issued-advisory-on-business-continuity-for-e-invoice-and-e-waybill-systems/
- CBIC Notification No. 10/2023-Central Tax, 10 May 2023 (e-invoicing threshold of ₹5 crore from 1 August 2023), text as reproduced at: https://taxonation.com/index.php/show-detail-news/1043784/e-invoicing-limit-reduced-to-5-crores-from-10-crores-from-1st-august-2023
- GSTN e-invoice master site (enablement status and IRP list): https://einvoice.gst.gov.in
Operational guidance, not tax advice. Rules and IRP onboarding terms change; confirm on the GSTN and NIC portals and with your tax advisor before acting.
E-Invoicing Is One Step. See the Whole Order.
Bring a real purchase order and watch it go from approval to IRN, e-way bill and GRN in one flow, then score it on the table above.