GST Invoice Format for Professional Services
Consultants, agencies, and firms — clean 18% service invoices with the right SAC.
Professional services — consulting, accounting, legal, IT — are the simplest GST billing there is: one or two service lines at 18% under a chapter-99 SAC. The complexity hides at the edges: place of supply for interstate clients, export invoices under LUT, and time-of-supply rules for retainers and advances.
What this invoice format must include
The right SAC per service
Management consulting 998311, IT consulting 998313, software development 998314, accounting 998222, legal 998212 — the SAC drives your GSTR-1 service summary.
Place of supply decides CGST/SGST vs IGST
For B2B services it's the client's registered location — a Delhi client billed from Mumbai means IGST, even for remote work.
Export invoices under LUT
Foreign-client invoices are zero-rated: bill without tax under a Letter of Undertaking, mention the LUT, and invoice in convertible foreign exchange.
Advances are taxable on receipt
Service advances trigger GST when received — issue a receipt voucher and adjust it on the final invoice.
Sample line items
Typical line items with the HSN/SAC codes and GST rates this trade uses.
| Description | HSN/SAC | Qty | Rate (₹) | GST |
|---|---|---|---|---|
| Management consulting retainer — September 2026 | 998311 | 1 | 75,000 | 18% |
| GST return filing — Q2 compliance | 998222 | 1 | 15,000 | 18% |
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Frequently asked questions
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