Construction and property
A structural engineer's GST invoice should name the project, the scope (structural design, proof checking, structural audit, retrofit design), the drawings or reports delivered, and the fee basis per square foot or lump sum. Engineering services fall under group 99833, such as 998331 to 998339 for engineering advisory, design and project management, and structural testing under 998346. They attract 18% GST. The invoice should also carry the engineer's licence or registration number where the local authority requires it.
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Or create these invoices in software, free| Description | HSN/SAC | Qty | Rate (₹) | Taxable (₹) | GST |
|---|---|---|---|---|---|
| Structural design and detailing of G+4 residential building, stage 1 (foundation drawings) | 998332 | 1 OTH | 95,000.00 | 95,000.00 | 18% |
| Proof checking of structural design for commercial building | 998332 | 1 OTH | 60,000.00 | 60,000.00 | 18% |
| Structural audit of 30-year-old housing society building with report | 998346 | 1 OTH | 75,000.00 | 75,000.00 | 18% |
| Site visits for reinforcement checking | 998332 | 5 NOS | 4,000.00 | 20,000.00 | 18% |
| Taxable value | ₹2,50,000.00 | ||||
| GST (CGST + SGST, or IGST if inter-state) | ₹45,000.00 | ||||
| Invoice total | ₹2,95,000.00 | ||||
Sample prices are illustrative. Check the GST rate for your exact item or service before billing.
Rule 46 of the CGST Rules applies to every tax invoice, including this one:
Read more: Billing for Service Businesses: Models, GST and Best Practice · What Is a SAC Code and How Is It Used Under GST? · Advance Payment Under GST: Receipt Vouchers, Tax and Adjustment
Engineering services are classified under group 99833 of the SAC annexure, with sub-codes for advisory, project management, and engineering for specific projects. Technical testing and analysis services fall under 998346. All are taxed at 18% under the entry for other professional, technical and business services. There is no concessional rate for structural design of affordable housing or Government buildings, unlike some works contracts.
Section 12(3) places services directly in relation to immovable property, including those of architects, interior decorators and engineers, at the location of the property. A structural design firm in Hyderabad designing a building in Chennai is therefore supplying a service in Tamil Nadu. Contractors and consultants with ongoing work in another state should consider registration there; the site address on the invoice supports the place of supply.
Many municipal bodies require periodic structural audits of older buildings. Housing societies commission these audits and pay from their funds. The audit is a taxable service at 18%; an unregistered society bears the tax as cost. Address the invoice to the society and mention the audit date and building identification as in the municipal notice.
If you engage a laboratory for core testing in your name and add the cost to your bill, the full amount is your taxable value. If the lab invoices the society directly and you merely coordinate, you exclude it from your bill. Keep the arrangement clear so tax is not paid twice or omitted.
Consultants often take an advance before starting design. GST on that advance is payable when received. If the project is cancelled and part of the advance is refunded, issue a refund voucher. Unrefunded advances retained as compensation remain taxable consideration.
When a structural audit leads to retrofitting, the consultant usually designs jacketing, carbon-fibre wrapping or underpinning, and a separate contractor executes it. Keep your design and supervision invoices under the engineering code at 18%, distinct from the contractor's works contract under 9954. If you take on execution as well, the execution portion becomes a works contract and should be invoiced separately from the design fee, so that each supply is reported under the right code.
Use the appropriate code in group 99833 for engineering services; structural design is commonly billed under 998332. Testing and analysis services use 998346.
Engineering consultancy and design services are taxed at 18%.
Yes. A structural audit is a taxable professional service at 18%, even if the society itself is not registered.
For buildings constructed on own account, section 17(5)(d) blocks credit on services used in construction. Builders selling flats under concessional real-estate rates cannot claim credit at all.
Place of supply is the site location. Consultants with regular work in another state should evaluate registration there with their adviser.
GST does not require it, but municipal bodies accept structural drawings and audit reports only from licensed engineers. Printing the licence number alongside your GSTIN saves clients from asking for it separately when they submit your documents.
Sources: CBIC — Scheme of Classification of Services (SAC annexure) · CBIC — Notification 15/2025-Central Tax (Rate) (services rates) · ICAI IDTC — Notification 9/2025-Integrated Tax (Rate) as corrected 18 Sep 2025
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