GST for Sub Contractors: Complete Guide to GST Rates, ITC & Compliance

Yes, GST registration is mandatory under Section 22 of the CGST Act if the aggregate annual turnover exceeds ₹20 lakh (or ₹10 lakh in specified special category states). Additionally, certain conditions trigger mandatory registration regardless of turnover under Section 24.

Mandatory Registration Triggers:

• Aggregate turnover exceeding ₹20 lakh (₹10 lakh in special category states).
• Making inter-state taxable supplies (taking a contract in another state).
• Providing job work services to a registered principal.
• Sub-contractors subject to reverse charge mechanism (RCM).

Voluntary registration is highly advisable to claim ITC on materials and to be part of the main contractor's ITC chain — most main contractors will only engage a GST‑registered sub‑contractor to ensure they don't lose out on input tax credit.

As per Notification No. 11/2017-Central Tax (Rate) (and subsequent amendments, notably the rationalization in 2022), the GST rate for sub‑contractors is uniformly 18% for works contract services (SAC 9954) and 18% for pure labour services to commercial clients (SAC 9985).

• Works Contract (Material + Labour): 18%
• Pure Labour (Commercial Client): 18%
• Pure Labour (Residential Homeowner): 0% (Exempt if no material is supplied)

Key Point: Post‑GST 2.0 reforms, the concessional 12% slab for certain government/affordable housing works contracts has been largely abolished; all works contract and manpower services are now uniformly taxed at 18% to remove inversion anomalies.

Government projects — roads, bridges, railways, dams, government buildings — often involve multiple layers of contracting. The main contractor, awarded the work by a government department, frequently engages sub‑contractors for specialised tasks. The GST treatment for such sub‑contractors is the same as for any works contract: 18% on the total contract value if they supply materials, or 18% under SAC 9985 if they supply only labour (since the main contractor is a business). The key additional compliance element is TDS under Section 51 of the CGST Act, 2017, which applies only when the payer is a specified person (government department, local authority, or government agency).

🔹 TDS Under Section 51 — Who Deducts and When

Section 51 mandates that the Central Government, a State Government, a local authority, or any other specified person must deduct TDS at 2% (1% CGST + 1% SGST or 2% IGST) on payments made to a supplier of taxable goods or services where the total value of such supply under a contract exceeds ₹2.5 lakh. The critical distinction for sub‑contractors is:

• Scenario A – Direct Contract with Government Department: If a sub‑contractor is engaged directly by a government entity (e.g., PWD directly hires a tiling sub‑contractor for a school building), the government department deducts TDS at 2% on each payment exceeding ₹2.5 lakh. The sub‑contractor must be GST‑registered to receive the TDS credit. The deducted TDS appears in the sub‑contractor's GSTR‑2A/2B and can be used to offset output tax liability in GSTR‑3B.
• Scenario B – Private Main Contractor Executing a Government Project: If the main contractor is a private limited company or partnership firm (not a government entity) and they engage a sub‑contractor, the main contractor does not deduct GST TDS under Section 51. GST TDS is only applicable when the payer is a specified person. The main contractor simply pays the sub‑contractor's invoice (including GST) and claims ITC. The government department deducts TDS only from the main contractor's payment, not from the sub‑contractor.

🔹 Registration and Invoicing Requirements

• Registration: A sub‑contractor working on a government project must be registered if TDS is to be deducted (to receive the credit) or if their aggregate turnover exceeds the threshold. Many government departments also require a GSTIN in the contract itself. Even if the sub‑contractor is below the threshold, voluntary registration is advisable to claim TDS credit.
• Tax Invoice: For works contracts, issue a tax invoice under SAC 9954. For pure labour, use SAC 9985. The invoice must show the government department's GSTIN (if direct) or the main contractor's GSTIN. Place of supply is the location of the immovable property (Section 12(3) IGST Act). If the project site is in a different state from the sub‑contractor's place of business, charge IGST.
• TDS Reconciliation: Every month, reconcile the TDS appearing in GSTR‑2A/2B with the payment certificate from the government department. Accept the TDS credit in GSTR‑3B. Unreconciled TDS leads to excess cash outflow because the sub‑contractor pays output tax in cash without utilising the TDS already deducted.

🔹 Pure Labour Contracts for Government Projects

Government departments sometimes award pure labour contracts where they supply all materials and the contractor provides only manpower. Such contracts are exempt under Notification No. 12/2017‑CT(R) Entry 10, provided the work relates to a civil structure or original works and no material is supplied by the contractor. If the sub‑contractor supplies even minor consumables (nails, sandpaper, sealing tape), the entire contract becomes a taxable works contract. For exempt labour contracts, the sub‑contractor must issue a Bill of Supply without GST. The government department may still deduct TDS (because the contract value exceeds ₹2.5 lakh), but since the supply is exempt, the TDS credit cannot be utilised and remains stuck in the Electronic Cash Ledger unless a refund is applied for under Section 54.

🔹 ITC Implications

Sub‑contractors on government projects can claim full ITC on materials, consumables, and overheads, as their output is taxable. This ITC must be matched with GSTR‑2B. If the government department supplies any materials free of cost, the sub‑contractor must add the value of such free‑issue material to the taxable value of the contract under Section 15(2)(b). Failing to do so results in short‑payment of GST.

Civil and electrical sub‑contractors form the infrastructure and services backbone of construction projects. Civil sub‑contractors handle earthwork, piling, roadwork, bridgework, drainage, and concrete structures. Electrical sub‑contractors undertake wiring, panel installation, lighting, power distribution, and low‑voltage systems. When these sub‑contractors supply both materials and labour, their services are works contracts under Section 2(119) of the CGST Act, 2017, taxable at 18% under SAC 9954. When they supply only labour (client supplies all materials), the service is manpower supply taxable at 18% under SAC 9985 (if the client is a business), or exempt if the client is an individual homeowner with no material supplied.

🔹 Classification and Rates

🔹 Place of Supply — The Most Critical Compliance Factor

For civil and electrical works, the place of supply is determined by Section 12(3) of the IGST Act, 2017. The place of supply of services directly in relation to an immovable property is the location of that immovable property. This rule applies regardless of where the main contractor's office is, or where the sub‑contractor is registered. The tax type (IGST vs CGST+SGST) depends entirely on whether the sub‑contractor has a registration in the state where the property is located.

• Same state as sub‑contractor's registration: Charge CGST + SGST. Example: A sub‑contractor registered in Maharashtra works on a road project in Pune, Maharashtra. Place of supply = Maharashtra → CGST + SGST.
• Different state from sub‑contractor's registration: Charge IGST. Example: The same sub‑contractor works on a road project in Madhya Pradesh. Place of supply = Madhya Pradesh → IGST. It does not matter that the main contractor's office is in Maharashtra.
• Sub‑contractor has separate GSTIN in the state of the property: If the sub‑contractor has obtained a separate registration in that state (e.g., for a project office), CGST + SGST can be charged using that GSTIN.

Getting the place of supply wrong is a common error with severe consequences: the main contractor cannot claim ITC on an invoice with incorrect tax type, and inter‑state mismatches are automatically flagged by the GSTN system. Always verify the project site state before raising the first invoice.

🔹 ITC Chain in Civil and Electrical Sub‑Contracts

The ITC flow is identical to any works contract chain:

• Material supplier → Sub‑contractor: Sub‑contractor purchases cement, steel, cables, panels, switches, and claims ITC at 18%.
• Sub‑contractor → Main contractor: Sub‑contractor issues tax invoice with 18% GST. Main contractor claims ITC.
• Main contractor → End client: Main contractor includes sub‑contract value in their own works contract invoice and charges GST. End client claims ITC if eligible.

A break at any point — e.g., sub‑contractor buying steel from an unregistered dealer — breaks the chain. Sub‑contractors must source from registered suppliers and ensure their invoices are uploaded in GSTR‑1.

🔹 Civil Sub‑Contractors — Special Considerations

• Government projects: Civil sub‑contractors on government roads, bridges, dams must charge 18% GST. If hired directly by the government department, TDS under Section 51 at 2% is deducted. Reconcile with GSTR‑7A monthly.
• Earthwork and excavation: If the sub‑contractor supplies only machinery and operator (JCB, excavator) with diesel, and no other material, the service is typically a supply of machinery on hire (18% GST). If the sub‑contractor also does the groundwork, it is a works contract.
• Rural road schemes (PMGSY): Construction of roads under PMGSY is exempt. Sub‑contractors working on such projects must not charge GST. They must issue a Bill of Supply and cannot claim ITC on inputs used for these projects.

🔹 Electrical Sub‑Contractors — Special Considerations

• Material‑intensive contracts: Electrical sub‑contracts often involve high‑value items like panels, cables, transformers, and lighting. ITC on these purchases is significant. Sub‑contractors must ensure every purchase is from a registered dealer with a proper B2B invoice.
• Pure labour electrical work: If the main contractor supplies all cables, panels, switches, and the sub‑contractor provides only electricians and fitters, the service is taxable at 18% under SAC 9985. The exemption for residential homeowners is not available because the main contractor is a business.
• e‑Invoicing: Electrical sub‑contractors with turnover above ₹5 crore must generate e‑invoices for all B2B supplies.

When a sub‑contractor is engaged by the main contractor to execute a specific portion of a project and supplies both materials and labour, the transaction is a works contract as defined in Section 2(119) of the CGST Act, 2017. Under Schedule II, Para 6(a) of the Act, a works contract is treated as a supply of service, not a supply of goods. The sub‑contractor is therefore providing a service to the main contractor, even though a significant portion of the contract value may represent materials. The entire contract — including raw materials, consumables, labour, and profit — is a single composite supply taxable at 18% under SAC 9954.

🔹 Legal Framework and Valuation

The works contract provided by a sub‑contractor is governed by the following provisions:

• Section 2(119) — Definition: Any contract for building, construction, fabrication, erection, installation, fitting out, improvement, modification, repair, maintenance, renovation, alteration, or commissioning of any immovable property where transfer of property in goods is involved. The sub‑contractor's work on a building, road, or electrical system falls squarely within this definition.
• Schedule II, Para 6(a): Works contracts are deemed to be a supply of services. This means the sub‑contractor is a service provider, and the entire contract value is the taxable value of that service.
• Section 15 — Valuation of Taxable Supply: The value is the transaction value — the total amount the main contractor pays to the sub‑contractor. It must include all costs: materials, labour, design, transportation, and any other charges. No deduction is allowed for the cost of materials. If the main contractor supplies any material free of cost, its value must be added to the sub‑contractor's taxable value under Section 15(2)(b).
• Notification No. 11/2017‑CT(R): Prescribes the rate of 18% (9% CGST + 9% SGST) for works contract services.

🔹 Composite Supply — One Invoice, One Rate

The sub‑contractor's works contract is a composite supply under Section 8 of the CGST Act. The principal supply is the service of executing the work. The materials (bricks, cement, steel, pipes, wires) are inputs that get consumed in providing the service. Therefore, the sub‑contractor must:

• Issue a single tax invoice under SAC 9954 for the total contract value.
• Charge a uniform 18% GST on the entire value. Even if the invoice shows a detailed breakup of material and labour costs for the main contractor's reference, the GST rate must be uniformly 18% on the total.
• Not split the invoice into separate goods and services components. Doing so is a misclassification that can lead to a demand of differential tax, interest, and penalty under Section 73 (10%) or Section 74 (100%).

🔹 The ITC Chain in Sub‑Contract Works Contracts

The works contract model creates a cascading Input Tax Credit chain that, when functioning correctly, ensures tax is only levied on the value addition at each stage:

• Stage 1 – Raw Material Supplier → Sub‑Contractor: The sub‑contractor purchases cement, steel, tiles, pipes, etc., from registered dealers. The dealer charges 18% GST. The sub‑contractor claims this GST as ITC in GSTR‑3B (subject to GSTR‑2B matching).
• Stage 2 – Sub‑Contractor → Main Contractor: The sub‑contractor issues a tax invoice under SAC 9954, charging 18% GST on the total contract value. The main contractor claims this GST as ITC, provided the sub‑contractor has uploaded the invoice in GSTR‑1 and it reflects in the main contractor's GSTR‑2B.
• Stage 3 – Main Contractor → End Client: The main contractor includes the sub‑contract work value in their own works contract invoice to the end client (builder, factory owner, government department). The main contractor charges 18% GST on the total. The end client claims ITC if eligible.

If the sub‑contractor fails to file GSTR‑1, the main contractor's ITC is blocked. This is why main contractors increasingly insist that sub‑contractors file returns on time. A single late filing by a sub‑contractor can disrupt the ITC chain for the entire project.

🔹 Place of Supply for Sub‑Contract Works Contracts

The place of supply is governed by Section 12(3) of the IGST Act, 2017 — it is the location of the immovable property where the work is executed. This rule applies irrespective of where the main contractor's office is located. The sub‑contractor must:

• Charge CGST + SGST if the property is in the same state as the sub‑contractor's registration.
• Charge IGST if the property is in a different state from the sub‑contractor's registration.

A common mistake is charging CGST+SGST based on the sub‑contractor's own state when the project is in another state — this renders the invoice invalid and blocks the main contractor's ITC.

🔹 Free‑Issue Material — Don't Forget to Add Its Value

If the main contractor supplies any material free of cost to the sub‑contractor (e.g., steel, cement, tiles), the value of such material must be included in the taxable value of the sub‑contractor's works contract under Section 15(2)(b) of the CGST Act. Failing to include this value results in short‑payment of GST. Example: The main contractor supplies tiles worth ₹1,00,000 free of cost. The sub‑contractor charges ₹50,000 for fixing labour. The taxable value is ₹1,50,000, not ₹50,000. GST @18% = ₹27,000.

Yes, absolutely. Under Section 9 of the CGST Act (Levy and Collection), a registered sub‑contractor must charge GST on every taxable forward supply. This includes works contracts, pure labour to commercial clients, and equipment rentals.

• If registered, you must issue a Tax Invoice and charge GST.
• The only exception is an exempt pure labour contract to a residential homeowner, where you issue a Bill of Supply.
• Even if the main contractor is unregistered, the registered sub‑contractor must still charge GST.

If the sub‑contractor is unregistered (turnover below threshold), they do not charge GST. However, the main contractor cannot claim ITC on purchases from an unregistered sub‑contractor. In certain notified real estate scenarios, the main contractor may even be forced to pay the tax themselves under the Reverse Charge Mechanism (RCM). This makes unregistered sub-contractors highly undesirable for large builders.

Yes, the main contractor can claim ITC on the sub‑contractor's invoice, provided the sub‑contractor is GST‑registered. Per Section 16(2)(aa), this ITC claim is strictly contingent on the sub-contractor uploading the invoice in their GSTR-1, ensuring it populates in the main contractor's GSTR-2B.

If the sub‑contractor fails to file GSTR-1, the main contractor loses the ITC, which directly impacts their project margins. The main contractor can claim the full ITC (18% of the taxable value) against their outward tax liability because they are utilizing the sub‑contractor's services to execute a further taxable supply.

Sub‑contractors are subject to standard GST return filing cycles as mandated by Sections 37 and 39 of the CGST Act:

• GSTR-1 (Outward Supplies): Due by the 11th of the following month (or 13th for QRMP filers). This is critical for passing on ITC to the main contractor.
• GSTR-3B (Summary & Payment): Due by the 20th of the following month (or 22nd/24th for QRMP filers). This is where tax is paid and input credit is claimed.
• GSTR-9 (Annual Return): Mandatory if aggregate turnover exceeds ₹2 crore in the financial year.

Sub-contractors with an aggregate annual turnover up to ₹5 crore can opt for the QRMP Scheme (Quarterly Return Monthly Payment), which reduces the filing burden to quarterly, though tax payments must still be deposited monthly via PMT-06.

• 1

  Not registering for GST despite aggregate turnover crossing the ₹20 lakh threshold

  Many sub‑contractors operate across multiple small projects and fail to maintain a consolidated turnover record. They assume that because each individual contract is small, they do not need registration. Under Section 22 of the CGST Act, 2017, what matters is the aggregate annual turnover — the sum of all taxable and exempt supplies across India. Even if every single contract is below the threshold, if the total crosses ₹20 lakh (₹10 lakh in special category states), registration is mandatory. Failure to register attracts a penalty of 10% of the tax due or ₹10,000, whichever is higher, under Section 122. Moreover, the main contractor cannot claim ITC on supplies from an unregistered sub‑contractor, which often leads to loss of contracts.

  Real Example: A plastering sub‑contractor works for three different builders in a year, earning ₹8 lakh, ₹7 lakh, and ₹6 lakh respectively. He thinks each contract is small, so he never registers. Total turnover = ₹21 lakh. He was liable to register, and the ₹21 lakh worth of supplies should have been taxed at 18%. The demand for GST on past supplies, plus interest and penalty, can financially cripple the business.

  Maintain a single ledger tracking all receipts from all projects. The moment aggregate turnover approaches ₹18 lakh, initiate the registration process on the GST portal. Even if you are below the threshold, consider voluntary registration — it allows you to issue tax invoices, claim ITC, and makes you a preferred sub‑contractor for main contractors who need to claim ITC.
• 2

  Misclassifying a works contract as pure labour — the "minor material" trap

  This is the single most frequent audit trigger for sub‑contractors. When a sub‑contractor supplies even a small quantity of material — a bag of cement, a tube of adhesive, a box of nails, a roll of soldering wire — the contract transforms from a pure labour service (SAC 9985) into a works contract (SAC 9954). The entire contract value, including labour, becomes taxable at 18% under the works contract rules. Many sub‑contractors continue to bill under SAC 9985 or, worse, issue a Bill of Supply claiming exemption, leading to significant short‑payment of GST. The department may invoke Section 73 (if considered a bona fide error) or Section 74 (if viewed as deliberate misclassification) and demand the differential tax with interest and penalty.

  Real Example: A waterproofing sub‑contractor uses his own sealant and primer worth ₹2,000 on a project while the main contractor supplied all other materials. He bills ₹1,00,000 as pure labour (SAC 9985). The department discovers the material supply. The entire ₹1,02,000 is re‑classified as a works contract. Short‑paid GST = ₹18,360 (18% of ₹1,02,000) minus ₹18,000 already paid = ₹360. Even though the amount is small, the penalty for misclassification can be up to 100% of the tax, and the main contractor's ITC may be blocked.

  If any material is supplied by you — no matter how small the value — classify the entire supply as a works contract under SAC 9954. Charge 18% GST on the total value (material + labour). Issue a single tax invoice. This ensures correct ITC for the main contractor and protects you from misclassification demands.
• 3

  Delaying or skipping GSTR‑1 filing — blocking the main contractor's ITC

  Under Rule 36(4) of the CGST Rules, a main contractor can claim Input Tax Credit only on invoices that have been uploaded by the sub‑contractor in their GSTR‑1 and appear in the main contractor's GSTR‑2B. If a sub‑contractor files GSTR‑1 late, or does not file it at all, the main contractor cannot claim ITC for that period. This directly impacts the main contractor's cash flow and often results in the sub‑contractor's payment being held back. In a competitive industry, a sub‑contractor who habitually delays filing will quickly lose business to compliant competitors.

  Real Example: A tiling sub‑contractor completes work in April but forgets to file GSTR‑1 until June. The main contractor, who files GSTR‑3B for April in May, finds the sub‑contractor's invoice missing from GSTR‑2B. The main contractor cannot claim ITC of ₹36,000. The builder refuses to release the sub‑contractor's payment until the ITC issue is resolved. The sub‑contractor also pays a late fee of ₹50 per day for the delayed GSTR‑1.

  File GSTR‑1 by the due date — 11th of the following month (or 13th of the next quarter under QRMP) — without exception. Set calendar reminders. Even if there are no invoices in a period, file a Nil GSTR‑1. If you are on the QRMP scheme, use the Invoice Furnishing Facility (IFF) for the first two months of the quarter to upload B2B invoices so the main contractor can claim ITC early.
• 4

  Charging CGST+SGST instead of IGST for inter‑state sub‑contract work

  The place of supply for a works contract is the location of the immovable property — Section 12(3) of the IGST Act, 2017. If a sub‑contractor registered in one state executes work at a project site in another state, they must charge IGST, not CGST+SGST. Many sub‑contractors erroneously charge CGST+SGST based on their own registration state, making the invoice legally incorrect. The main contractor cannot claim ITC on such an invoice, and the GSTN system automatically flags the inter‑state mismatch.

  Real Example: A sub‑contractor registered in Karnataka undertakes waterproofing work at a project in Telangana. The sub‑contractor charges CGST+SGST (Karnataka) on the invoice. The main contractor in Telangana cannot claim ITC because the correct tax type is IGST. The sub‑contractor must issue a credit note and a corrected IGST invoice, causing administrative delay and potential penalty.

  Before issuing any invoice, confirm the state where the project site is located. If it differs from your registration state, charge IGST. Use billing software that auto‑populates the tax type based on the place of supply entered. Train your accounts staff on this critical distinction.
• 5

  Not reconciling GSTR‑2B before claiming ITC in GSTR‑3B

  Sub‑contractors purchase materials from multiple dealers — cement, steel, tiles, pipes, hardware — and record these purchases in their accounting software. However, under Rule 36(4), ITC can be claimed only to the extent it appears in GSTR‑2B. Many small dealers fail to upload invoices in GSTR‑1. If a sub‑contractor claims ITC on such missing invoices, the system auto‑generates a Show Cause Notice for excess ITC. This is among the top reasons for GST demand notices to sub‑contractors.

  Real Example: A sub‑contractor buys cement worth ₹1,00,000 (GST ₹18,000) from a local dealer who does not file GSTR‑1. The sub‑contractor claims the ₹18,000 as ITC in GSTR‑3B. The department matches GSTR‑3B with GSTR‑2B and finds the mismatch. The excess ITC of ₹18,000 is reversed with 18% interest and a penalty.

  Download GSTR‑2B from the GST portal after the 14th of each month. Match every purchase invoice line‑by‑line with GSTR‑2B. Claim only the ITC that appears in GSTR‑2B. Follow up with suppliers whose invoices are missing. Make supplier compliance a condition in your purchase orders.
• 6

  Not adding the value of free‑issue material from the main contractor to the taxable value

  Main contractors often supply certain materials free of cost to sub‑contractors (e.g., tiles, cement, steel). Under Section 15(2)(b) of the CGST Act, the value of such free‑issue material must be included in the taxable value of the sub‑contractor's works contract. Many sub‑contractors charge GST only on their labour and profit, ignoring the free‑issue material. This results in a significant short‑payment of GST, which the department can demand with 18% interest and penalty.

  Real Example: A main contractor supplies tiles worth ₹2,00,000 free of cost to a tiling sub‑contractor. The sub‑contractor charges ₹80,000 for labour and fixing. The sub‑contractor pays GST on ₹80,000 = ₹14,400. The correct taxable value is ₹2,80,000 (₹2,00,000 + ₹80,000). GST payable = ₹50,400. Shortfall = ₹36,000 plus interest.

  When entering into a sub‑contract, clarify whether any materials will be provided free of cost by the main contractor. Maintain a record of such materials. Add their value to your invoice's taxable value and charge GST on the total. If the exact value is not known, obtain a written confirmation from the main contractor.
• 7

  Issuing a Bill of Supply instead of a Tax Invoice for taxable supplies

  Some sub‑contractors, especially those providing labour‑only services to a main contractor, mistakenly believe that because they are not supplying materials, their service is exempt. They issue a Bill of Supply without GST. However, the exemption for pure labour contracts under Notification 12/2017‑CT(R) is only available when the service recipient is an individual homeowner. When the recipient is a business (the main contractor), the service is taxable at 18% under SAC 9985. Issuing a Bill of Supply in such cases means the sub‑contractor has not charged GST, resulting in a demand for the unpaid tax plus interest and penalty.

  Real Example: A labour sub‑contractor provides masons to a builder for a residential project. He issues a Bill of Supply for ₹2,00,000 without GST, assuming the work is residential and therefore exempt. The builder is a company, not an individual homeowner. The correct treatment is a tax invoice under SAC 9985 with 18% GST = ₹36,000. The sub‑contractor now owes ₹36,000 + interest + penalty.

  Check the identity of your client before issuing any document. If the client is a business (builder, company, firm), your supply is taxable — issue a Tax Invoice and charge 18% GST. A Bill of Supply is only for exempt supplies to an individual homeowner under Notification 12/2017.
• 8

  Not filing Nil returns during lean periods — risking registration cancellation

  Sub‑contracting work is often seasonal or project‑based. During months with no projects or billing, some sub‑contractors skip filing GSTR‑1 and GSTR‑3B, assuming "no business means no return." This is incorrect. A Nil return must be filed for every period. Gaps in filing attract late fees, damage the compliance rating, and can lead to cancellation of GST registration under Section 29(2) if returns are not filed for six consecutive months. Once registration is cancelled, the sub‑contractor cannot issue valid invoices or claim ITC, effectively putting them out of business.

  File Nil GSTR‑1 and Nil GSTR‑3B for every month or quarter with no activity. Late fees for Nil returns are lower (₹20/day). Set recurring calendar reminders. Maintaining an uninterrupted filing history is essential for business continuity and credibility with main contractors.

• Register via Form GST REG-01 if turnover > ₹20L or making inter-state supplies.
• Classify contract accurately – Composite Works Contract (SAC 9954) vs. Pure Labour (SAC 9985).
• Charge 18% GST on all forward taxable supplies to contractors.
• Issue Rule 46 compliant Tax Invoices displaying correct Place of Supply.
• Upload B2B invoices in GSTR‑1 or IFF on time to ensure main contractor ITC.
• Reconcile purchase invoices with GSTR‑2B before claiming ITC in GSTR-3B.
• File GSTR‑3B and remit net tax liability by the statutory due date.
• Maintain strict project‑wise accounting records and material registers.