GST + e-Invoice APIs for Construction — Works Contract, RCM, Advances

Works-contract GST (12%/18% split), RCM on consultancy + JCB hire, advance vs running-bill IRN.

The problem

Civil construction works-contract is 12% (govt) or 18% (private); RCM on sub-contracted consultants + heavy equipment. Advance vs running-bill IRN linkage is messy.

How WhiteBooks solves it

WhiteBooks is a GSP-certified API platform with direct connectivity to GSTN, NIC e-Way Bill, and IRP. Construction customers use the same OAuth token across all their GSTINs, with sandbox-by-default and idempotency keys on every state-mutating call.

Key APIs

• einvoice.generate_irn
• gst.file_gstr3b (RCM)
• eway.generate (material movement)

Compliance angle

GSP-licensed gateway, 99.99% SLA with credits, ISO 27001 + DPDP Act 2023 compliant audit trail (7-year retention). All API calls are TLS 1.2+ with OAuth 2.0 client_credentials. Sandbox at whitebooks.in is free with no credit card.

Live numbers

• Throughput: 1,000 invoices / EWBs per single API call (bulk mode).
• Latency: p50 87 ms IRN, p95 312 ms — live at whitebooks.in/status.
• Uptime: 99.994% rolling 30-day; 99.99% SLA with credits on Enterprise.

Related: All APIs hub · GST docs · e-Invoice docs · e-Way Bill docs · OpenAPI specs · Status · Changelog