How GST Applies to Construction
Construction is covered under GST through two distinct mechanisms: supply of goods (materials) and supply of services (construction activity). Most materials attract GST at the goods rate applicable to that commodity. Construction activity — where a contractor supplies both materials and labour to construct a structure — is treated as a 'works contract' under Section 2(119) of the CGST Act and attracts GST as a service.
The key distinction that determines your GST rate is whether the construction is for an affordable residential unit, a regular residential unit, or a commercial property, and whether the supplier (developer or contractor) is claiming input tax credit (ITC). These combinations produce different effective rates. Getting the classification right is not optional — it determines your output tax liability and your ITC eligibility.
Materials: Common GST Rates
Cement: 28%. Steel (TMT bars, structural sections): 18%. Sand and aggregate: 5% (natural), 18% (washed and processed). AAC blocks: 12%. Clay bricks: 12% (with fly ash content ≥25%) or 12% (standard red brick — reduced from 5% in 2022). Ready-mix concrete: 18%. Electrical wires and cables: 18%. PVC pipes: 12%. Tiles: 18% (ceramic), 18% (marble/granite slabs). Paint: 18%. Plywood and wood products: 12–18% depending on type.
Input Tax Credit on materials is available to a registered contractor when the materials are used in taxable works contracts. If you are providing services to a government entity on a contract that is exempt (like affordable housing below a certain threshold), you cannot claim ITC on inputs. The mismatch between paying GST on inputs and not charging GST on outputs — without being able to claim a refund — is a structural cost disadvantage in exempt supply contracts. Know your contract's GST treatment before pricing it.
Works Contract GST Rates
Works contracts for construction of residential complexes (other than affordable housing) where the developer sells before completion: 5% without ITC (most common), or 12% with ITC (rare choice). Works contract for affordable housing (as defined by GST law — carpet area below 60 sqm in metros, 90 sqm elsewhere, and value below ₹45 lakh): 1% without ITC. Works contracts for commercial properties: 12% with ITC. Works contracts for government civil works (roads, bridges, dams, airports — civil infrastructure): 12% with ITC. Subcontract work (a contractor hiring a sub-contractor on a government civil infrastructure contract): 12%.
The most common error made by MSME contractors is treating a residential sub-contract as a commercial works contract or vice versa — this can produce a 7% rate error on the entire contract value. A single residential project at ₹2 crore with a 7% rate error is ₹14 lakh of incorrectly charged GST — enough to trigger a show-cause notice on audit.
Practical Compliance Steps
Register for GST if your annual turnover exceeds ₹20 lakh (₹10 lakh for special category states). File GSTR-1 monthly or quarterly (depending on scheme), and GSTR-3B for payment. Reconcile your purchase invoices against GSTR-2B monthly — ITC is only available if the supplier has filed their GSTR-1. Many small material suppliers are non-compliant filers, which means their invoices appear on your books but the ITC is ineligible. Audit this quarterly.
An important protection: maintain a separate, project-wise ledger of all GST-paid invoices and ITC claimed. When the GST department conducts an audit (which is increasingly common for contractors above ₹1 crore turnover), this ledger, matched to your tax returns, is your primary defence. Engage a GST-experienced CA — construction GST is complex enough that generic tax advice leads to expensive errors.