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Indian manufacturers running factory expansion, civil works, plant maintenance and turnkey installation contracts struggle to reconcile contractor RA (running account) bills against the PO because of composite supply complexity (goods and services bundled), the 12% vs 18% GST rate split for specified categories, Section 17(5) blocked credit on building works, retention and mobilisation advance recovery accruals, and Section 393(1)(a) TDS calculated on the gross bill — producing a long-tail of stuck contractor payments and ITC mis-claims.
Classify each works contract by immovable vs movable property (Section 2(119) test), by rate category (12% concessional vs 18% standard), and by ITC eligibility (blocked under Section 17(5) for building/civil, allowed for plant and machinery foundation); on each RA bill apply retention deduction, mobilisation recovery, material recovery, and TDS under Section 393(1)(a) code 1002 on the gross value excluding GST; reconcile cumulative retention held, mobilisation balance and material recovery across the contract life.
Works contract master with contract type (immovable/movable), GST rate (12%/18%), ITC eligibility flag (blocked/allowed/plant-machinery), retention percentage, mobilisation advance balance, material recovery rate, contractor PAN/GSTIN, Section 393(1)(a) TDS rate (1%/2%), threshold tracker per PAN, and RA bill ageing buckets.
A clean works contract ledger where each RA bill ties to the PO, retention held accumulates to the contract retention account, mobilisation balance reduces with each recovery, TDS deducted at 1% or 2% on the correct base ties to the monthly Section 393 challan and quarterly Form 26Q, ITC is claimed only on the plant-and-machinery portion (not on blocked building works), and final retention release at defect liability period closure ties back to the original holdback ledger.
A finance controller at a textile manufacturer in Tirupur reviews the AP queue and finds ₹3.4 crore of contractor running account bills stuck across 14 active works contracts — a new dyeing-unit expansion, three civil works tenders, two plant maintenance AMCs, and eight smaller turnkey installations. The reasons the queue is stuck are the same reasons works contract reconciliation India is one of the hardest AP problems at any factory: the bills are composite supplies (goods plus services), the GST rate could be 12% or 18% depending on the category, ITC is blocked on building works but allowed on plant and machinery foundation, retention and mobilisation advance recoveries change every bill, and TDS under Section 393(1)(a) has to be computed on the gross value excluding GST. This guide covers each piece and how to reconcile it without breaking the law or the contractor relationship.
What a works contract is under Indian GST law
A works contract is defined under Section 2(119) of the CGST Act, 2017 as a contract for building, construction, fabrication, completion, erection, installation, fitting out, improvement, modification, repair, maintenance, renovation, alteration or commissioning of any immovable property wherein the transfer of property in goods (whether as goods or in some other form) is involved in the execution of such contract. The definition has two structural features: it applies only to immovable property, and it is necessarily a composite supply of goods and services. Under Schedule II of the CGST Act, a works contract is taxed as a supply of services — even though the contractor is supplying steel, cement, paint and other goods alongside labour. This single classification simplifies the GST treatment but creates downstream tax complications.
Contracts that involve movable property (for example fabrication of a piece of machinery delivered to the factory gate, or installation of a movable equipment skid) are not works contracts. They follow normal goods or composite supply rules, with the rate determined by the principal supply test under Section 8 of the CGST Act. AP teams that classify every “installation” or “fabrication” PO as a works contract by default mis-apply both the GST rate and the ITC blocking rule.
The 12% vs 18% rate split
The standard rate on works contract services is 18% GST. A concessional 12% GST rate applies to specified categories notified by the government — most commonly:
- Affordable housing projects meeting the carpet area and value thresholds prescribed in the rate notifications
- Government-funded infrastructure: roads, bridges, water supply, sewerage, public transport facilities
- Historical monuments, archaeological sites and pilgrimage facilities
- Works contracts for government departments, local authorities, governmental authorities or government entities, where the contract is for non-commercial use
For a manufacturer, the practical question is whether the contractor’s RA bill carries the correct rate. A new factory building or expansion for own commercial use is squarely 18% — there is no 12% concession for private commercial construction. A government-mandated effluent treatment plant funded under a state PCB programme might attract 12% depending on the notification language. The reconciliation control is to validate the rate against the contract category at PO stage, not at bill stage.
Section 17(5) blocked credit on works contract
This is where works contracts cost more than the contract value suggests. Section 17(5)(c) and (d) of the CGST Act blocks input tax credit on:
- Works contract services when supplied for construction of an immovable property (other than plant and machinery), except where it is an input service for further supply of works contract service
- Goods or services or both received by a taxable person for construction of an immovable property (other than plant and machinery) on his own account
So a manufacturer constructing a factory shed, office building, parking structure, perimeter wall or staff canteen for own use cannot claim ITC on the contractor’s GST. The 18% (or 12%) GST charged becomes a hard cost capitalised into the asset value. The carve-out is plant and machinery, defined to include the foundation and structural support necessary for fixing the plant — for example the concrete foundation of a heavy press, the structural steel for an overhead crane gantry, the piping support for a process line. ITC on the works contract portion attributable to plant-and-machinery foundation is allowed.
In practice the reconciliation has to split each works contract bill into a blocked component and an allowed component, with documentary support (engineering drawings, capitalisation schedule) for the allowed portion. AP teams that book the entire GST as ITC on a mixed civil-and-foundation contract face a reversal with 18% interest if unwound after September of the following financial year.
TDS treatment under Section 393(1)(a)
Works contract payments fall under Section 393(1)(a) of the Income Tax Act 2025, which replaced the legacy Section 194C. The TDS payment code on the monthly challan is 1002. Rates:
- 1% TDS when the contractor is an individual or HUF
- 2% TDS when the contractor is a company, firm, LLP, AOP, BOI or any other non-individual entity
The per-transaction threshold of ₹30,000 and the aggregate per-contractor per-year threshold of ₹1 lakh remain unchanged from the previous regime. TDS is deducted on the gross bill value excluding GST when GST is separately shown on the invoice; if GST is not separately disclosed, the deduction applies on the full invoice value. The deducted TDS goes into the monthly challan deposited by the 7th of the following month (30 April for March deduction), with the contractor’s PAN tagged. The quarterly Form 26Q reports the deduction, and the contractor sees the credit in Form 26AS / AIS. For the consolidated payment code map see TDS payment codes 1001-1092 India and for the cross-era handling between 194C and 393(1)(a) see Section 393 TDS new Income Tax Act reconciliation.
The RA bill commercial structure
A typical works contract running account (RA) bill — number 7 of 14 across an 18-month dyeing unit expansion, say — carries the following structure:
| Line | Computation |
|---|---|
| Gross bill value (work executed this cycle) | ₹42,00,000 |
| Less: retention at 7.5% | (₹3,15,000) |
| Less: mobilisation advance recovery at 15% of gross | (₹6,30,000) |
| Less: material supplied by manufacturer (cement, steel) | (₹4,20,000) |
| Sub-total before tax | ₹28,35,000 |
| Add: GST at 18% (on gross ₹42L, not on net) | ₹7,56,000 |
| Less: TDS under Section 393(1)(a) at 2% on gross ₹42L | (₹84,000) |
| Net payable to contractor this cycle | ₹35,07,000 |
The reconciliation traps in this structure are familiar:
- GST is applied on the gross, not on the net after retention and material recovery. Contractors who compute GST on the net are under-charging — a problem when the manufacturer later claims ITC (where allowed) on the higher GST amount the contractor reports in GSTR-1.
- TDS is on the gross excluding GST, not on the net payable. Deducting TDS on the net under-deducts and creates a Section 393 short-deduction exposure.
- Retention accumulates to a contract-specific retention ledger; it is released only on defect liability period closure (typically 12 months post-completion) and must reconcile back to the sum of all retentions held across all RA bills.
- Mobilisation advance recovery runs until the original advance is fully recovered; over-recovery (recovering more than was advanced) and under-recovery (final bill closed with mobilisation outstanding) are both common.
- Material supplied must reconcile to the manufacturer’s own inventory issue ledger to the contractor’s site — see the retention money pattern for the structured approach to holdbacks and recoveries.
Reference: variance taxonomy on works contract bills
| Variance code | Description | Resolution |
|---|---|---|
| RATE_GST_WRONG | Contractor applied 12% where 18% required (or vice versa) | Vendor credit note, restate ITC |
| ITC_BLOCKED_CLAIMED | ITC claimed on Section 17(5) blocked portion | Reverse with 18% interest if past September |
| RETENTION_NOT_DEDUCTED | RA bill paid without retention recovery | Manual journal; pursue contractor refund |
| MOBILISATION_OVER_RECOVERED | Cumulative recovery exceeds advance | Refund to contractor; correct ledger |
| TDS_BASE_WRONG | TDS computed on net instead of gross-ex-GST | Short-deduction; restate Form 26Q |
| MATERIAL_NOT_DEDUCTED | Manufacturer-supplied material not adjusted | Recover from contractor next bill |
What automated works contract reconciliation changes
A multi-plant manufacturer with 10-20 active works contracts at any time cannot run this on spreadsheets without leakage. The contracts span 12-24 months, generate 8-15 RA bills each, and require live tracking of three accruals (retention, mobilisation, material) per contract per bill, on top of the standard PO-GRN-invoice three-way match for materials and the GST/TDS treatment. Purpose-built reconciliation software India for manufacturing carries the works contract sub-model in its preset library, applies the Section 17(5) ITC split at bill stage, computes Section 393(1)(a) TDS on the right base, and surfaces retention and mobilisation balances on a contract-by-contract dashboard. Build is two-to-four weeks on AWS Mumbai (ISO 27001:2022), with the manufacturer’s match rate moving from the typical 51% baseline to 88% across the broader AP surface. For the headline three-way match rail see three-way matching software India, and for the pillar guide to all five manufacturing reconciliation rails see manufacturing reconciliation in India.
The current text of Section 2(119), Section 17(5) and the active rate notifications is on the GST portal.