GST API Integration with SAP and Tally: e-Invoice, e-Way Bill and Return Filing Options

GST API integration with SAP and Tally lets your ERP send invoices straight to the Invoice Registration Portal (IRP), get the IRN and signed QR code back on the invoice, raise e-way bills, and push return data to the GST portal without manual uploads. SAP and TallyPrime are the two most common systems in Indian finance teams, but they approach integration very differently. SAP is usually connected through an integration layer and a GSP. TallyPrime has its own built-in connected e-invoicing.

This guide explains the options for each, when a third-party GST API makes sense, and what to check before you start. For an overview of every API and ERP Figment connects to, see our GST API integration page.

What a GST API integration covers

Through the API, the ERP generates and cancels e-invoice IRNs, raises and updates e-way bills, pushes and fetches return data, and verifies GSTINs. All of these reach the government systems through a GST Suvidha Provider (GSP), either one you choose or one built into your software.

GST API integration with SAP

How SAP handles India e-invoicing

SAP's India e-invoicing solution is built on its eDocument framework. When a billing document is posted, an eDocument is created and its status is tracked in the eDocument Cockpit. The invoice data is sent by API call, through a cloud or on-premise integration layer, to a GSP, which forwards it to the IRP. SAP's own guidance is that you need a tie-up with a GSP, and that the invoice output should ideally be printed only after the IRN has been received in the eDocument Cockpit.

Integration options for SAP ECC and S/4HANA

SAP Business ByDesign works differently. SAP notes that ByDesign cannot support full end-to-end integration with the e-invoice system out of the box. It offers a JSON file approach (generate the IRN request file, upload it to the e-invoice portal, upload the response back) and a synchronous GSP approach set up through an implementation partner.

What to plan for in an SAP project

• Output control: the invoice print or PDF should wait for the IRN and QR code
• Document types: map billing types to INV, CRN and DBN, and supply types (B2B, exports, SEZ, and RCMDOM and RCMIMP for RCM self-invoices from 1 January 2027)
• Cancellation: link the SAP cancellation of a billing document to IRN cancellation within the 24-hour window, and to a credit note after it
• Multi-GSTIN: map each company code and plant to the right GSTIN and API credentials
• Error feedback: show IRP error codes in the cockpit or a custom report so billing teams can fix and resubmit

GST API integration with Tally

TallyPrime's built-in e-invoicing

TallyPrime has connected e-invoicing built in. Tally is itself a GSP, and TallyPrime's online e-invoicing requests are processed through Tally GSP. Once "Allow e-Invoicing" is set to Yes in the sales voucher type, TallyPrime sends the invoice to the IRP and fetches the IRN and QR code within seconds. If "Enable e-Way Bill" is also set, it generates the e-way bill in the same process. When the IRP is not reachable, TallyPrime can export e-invoice data as a JSON file. Tally's help documentation covers sales invoices, POS invoices, debit and credit notes, and from Release 3.0 e-invoices can be generated for any GSTIN.

For many small and mid-sized businesses running only on TallyPrime, this built-in route is enough.

When Tally users need a separate GST API

A separate GSP API connected to Tally makes sense when:

• Tally is one of several systems. A group with SAP at head office and Tally at branches wants one GSP, one log and one reconciliation across all GSTINs.
• Billing happens outside Tally. Invoices come from a billing app, e-commerce platform or custom system, and Tally is used only for accounts.
• Volumes are high. Bulk IRN generation, scheduled e-way bill updates or multi-IRP fallback are needed.
• Returns and reconciliation are run centrally. GSTR-1, GSTR-2B and IMS work is done in dedicated GST software that pulls data from Tally.

In these cases the integration is usually built by your Tally partner, with a Tally customisation (TDL) or a connector that reads vouchers from Tally, calls the GST API and writes the IRN, QR and e-way bill number back to the voucher.

SAP vs Tally: integration at a glance

Pre-integration checklist

How Figment connects to SAP and Tally

Figment Global Solutions is a GSTN-authorised GSP. Its e-Invoice API and e-Way Bill API work with SAP ECC and S/4HANA and Tally Prime. They are REST/JSON APIs on the official IRP and NIC interfaces, and e-invoices are routed across two or more IRPs for failover. The same APIs also work with Oracle, Microsoft Dynamics 365 and in-house systems; see the GST API integration page.

To start, you request sandbox access. Figment's API team confirms your use case and emails sandbox credentials with test GSTINs, sample payloads, the Postman collection and documentation. The team helps with field mapping, testing and go-live on every working day, and production keys typically follow within two weeks of sandbox access.

The GSP APIs also cover return filing (GSTR-1, GSTR-3B, GSTR-9/9C, IMS), so one provider can serve both e-invoicing and returns. For teams that want a ready application rather than building their own reports, GSTCPC handles GST returns, reconciliation and e-invoice and e-way bill generation from the same records.

Key takeaways

• SAP integrates through its eDocument framework or a direct GSP connector. Either way you need a GSP.
• TallyPrime has built-in e-invoicing and e-way bill generation through Tally GSP.
• Tally users need a separate GST API mainly for multi-system groups, external billing or central reconciliation.
• Map document types, clean masters and plan cancellations before you start.
• Test every case in a sandbox before production keys are issued.