GST Billing App for Contractors India — Free, Simple and AI-Powered
If you are a contractor in India — whether you do civil construction, electrical work, plumbing, interior design, IT services, or any other contract-based work — billing your clients correctly under GST is something you deal with on every single project.
And for most contractors, it is also the most confusing part of running the business.
Which SAC code applies to your work? Do you charge GST on materials and labour separately? What happens when your client is in a different state? How do you handle advance payments vs final billing?
This guide answers all of that — and shows you how GST Maker makes contractor billing fast, accurate, and completely free.
The Unique GST Billing Challenges Contractors Face
Contractors have a different billing situation compared to regular product sellers or pure service providers. Their work often involves a mix of materials and labour, multi-stage payments, and projects that span weeks or months.
Mixed supply of goods and services — A civil contractor supplies cement, steel, and tiles (goods) along with labour (service). Getting the GST treatment right for a mixed contract is not always straightforward.
Works contract — a special GST category — Under GST, construction and civil work is treated as a "works contract" — a specific category that has its own rules, SAC codes, and tax rates. Many contractors do not know this and use generic SAC codes, which creates compliance issues.
Advance payments and milestone billing — Contractors often receive payments in stages — 30% advance, 40% on completion of structure, 30% on handover. Each payment stage needs to be invoiced correctly.
Clients across states — An electrical contractor based in Delhi may work on a project in Noida (UP) or Gurugram (Haryana). Different states mean different GST treatment.
Sub-contractor relationships — Many contractors hire sub-contractors for portions of the work. The GST treatment of sub-contractor payments adds another layer of complexity.
GST Maker simplifies all of this into a fast, guided invoicing process that any contractor can use without an accounting background.
SAC Codes for Different Types of Contractors
One of the most important — and most confusing — parts of contractor billing is finding the right SAC code. Here are the most commonly used ones:
| Type of Contractor | SAC Code | GST Rate |
|---|---|---|
| Civil construction — new residential building | 995411 | 12% |
| Civil construction — commercial building | 995412 | 18% |
| Civil construction — roads, bridges, tunnels | 995431 | 12% |
| Electrical work and installation | 995461 | 18% |
| Plumbing and sanitary work | 995462 | 18% |
| HVAC installation (AC, ventilation) | 995463 | 18% |
| Interior design and decoration | 995478 | 18% |
| Painting and finishing work | 995473 | 18% |
| IT infrastructure setup and maintenance | 998314 | 18% |
| Facility management services | 998571 | 18% |
| Security services | 998521 | 18% |
| Landscaping and horticulture | 998536 | 18% |
| Solar panel installation | 995461 | 12%* |
| General works contract (mixed) | 9954 | 18% |
*GST rate on solar may vary based on specific components — always verify with your CA for large projects.
GST Maker's AI Magic Fill suggests the correct SAC code as you type your service description — so you spend less time looking up codes and more time doing your actual work.
How GST Maker Works for Contractors
Set Up Your Profile in 5 Minutes
Enter your business name, GSTIN, address, and logo. Done once, auto-filled on every invoice forever.
Save Your Services With SAC Codes
Add your standard services — civil work, electrical installation, plumbing, whatever you do — with the correct SAC code, your standard rate, and GST rate. Once saved, adding a service to an invoice is one click.
Handle Milestone-Based Billing Easily
For projects with stage-wise payments, GST Maker lets you create separate invoices for each milestone — advance invoice, progress invoice, and final invoice — all linked to the same project and client. Every invoice is correctly numbered and GST-compliant.
Use Proforma Invoices for Advance Payments
Before a client pays an advance, send them a proforma invoice. It gives them a formal document to process the payment internally. When the work is done, convert it to a tax invoice with one click.
Let AI Handle CGST vs IGST
If your client's project is in a different state from where your business is registered, GST Maker's AI Magic Fill automatically applies IGST instead of CGST + SGST. No manual decision needed.
Share on WhatsApp Instantly
On a construction site with no printer? No problem. Generate the invoice on your phone, copy the share link, and send it to your client on WhatsApp. They open a clean, professional invoice instantly.
Real Example — A Civil Contractor in Pune
Ramesh is a civil contractor based in Pune, Maharashtra. He handles residential construction projects ranging from ₹10 lakh to ₹1 crore. He works with individual homeowners, real estate developers, and housing societies.
His billing used to be a mess — handwritten bills for small clients, rough Excel sheets for developers, and no proper invoice numbering. His CA would spend hours at year end sorting through a pile of papers.
With GST Maker:
For a residential project in Pune (same state): - SAC code 995411 (residential construction) - 12% GST applies - CGST 6% + SGST 6% automatically applied - Milestone invoices created for advance, slab completion, and handover
For a commercial project in Mumbai (same state): - SAC code 995412 (commercial construction) - 18% GST applies - CGST 9% + SGST 9% automatically applied
Ramesh now creates every invoice in under 2 minutes from his phone on site. His CA is happy. His clients get professional documents. His GSTR-1 is ready at month end with one click.
Real Example — An Electrical Contractor in Delhi
Suresh is an electrical contractor based in Delhi. He installs electrical wiring, switchboards, and panels for residential apartments, offices, and commercial spaces. His clients are in Delhi, Gurugram (Haryana), and Noida (UP).
For years he sent handwritten bills. Some clients — especially corporate offices — kept asking for proper GST invoices. He lost one big contract because he could not provide a GST-compliant invoice on time.
With GST Maker:
Delhi client (same state): - SAC code 995461 (electrical installation) - 18% GST — CGST 9% + SGST 9% automatic
Gurugram client (different state — Haryana): - Same SAC code - 18% GST — IGST 18% automatic
Noida client (different state — UP): - Same SAC code - 18% GST — IGST 18% automatic
Suresh never has to think about which tax type to apply. He just selects the client and everything is handled. He won back corporate clients because his invoices now look professional and are fully compliant.
Real Example — An Interior Designer in Bengaluru
Priya runs an interior design studio in Bengaluru, Karnataka. She handles full home interiors — design, procurement of materials, and execution. Her projects range from ₹5 lakh to ₹50 lakh.
Her billing is complex because she charges separately for design fees (pure service), material procurement (goods resale), and installation labour (works contract). Three different billing types on one project.
With GST Maker: - Design fees — SAC 998392 (design services) — 18% GST - Material supply — HSN codes for furniture, tiles, lights — 12% or 18% GST depending on item - Installation and execution — SAC 995478 (interior works contract) — 18% GST
GST Maker handles all three invoice types cleanly. Priya creates separate invoices for each component, all linked to the same client. Her clients get proper documentation for every rupee they pay.
Handling Works Contract GST — The Special Rules
For construction and civil contractors, GST has a special category called works contract. This is where many contractors go wrong.
A works contract is defined as a contract where both goods and services are supplied together — like building a house where you supply cement, bricks, and labour all in one contract.
Under GST, works contracts are treated as services (not goods), and the applicable SAC code starts with 9954. The GST rate is:
- 12% for contracts related to affordable housing, government projects, and certain infrastructure work
- 18% for all other construction, commercial, and civil works contracts
Key point: In a works contract, you cannot separately value materials and labour to apply different GST rates. The entire contract value is taxed as a service at the applicable works contract rate.
Many contractors mistakenly try to split their bills — charging 0% or lower rates on materials and higher rates on labour — to reduce the total GST burden. This is not compliant under GST works contract rules and can create issues during audits.
GST Maker helps you apply the correct works contract SAC code and rate automatically — keeping you compliant and avoiding problems later.
GST Maker Features Contractors Use Most
Tax Invoice — Fully compliant GST invoices with SAC codes, correct tax types, sequential numbering, and professional PDF format.
Proforma Invoice — Send before collecting advance payment. Perfect for milestone-based contractor billing. Convert to tax invoice with one click.
Quotation — Share a detailed project quote before confirming the contract. Convert to proforma and then to tax invoice as the project progresses.
Expense Tracker — Track your material purchases, sub-contractor payments, and site expenses. Essential for ITC claims and project cost tracking.
Client Management — Save all your clients — developers, housing societies, corporates — with their GSTIN and address. One-click selection on every invoice.
AI Magic Fill — Auto-detects CGST/SGST vs IGST based on project location, suggests SAC codes, calculates taxes. Works perfectly for multi-state contractor work.
GST Reporting — GSTR-1 ready report at month end. All invoice data organized and ready for your CA or for direct filing.
Public Share Link — Share invoices directly on WhatsApp from your phone on site. No printer, no laptop, no delay.
Frequently Asked Questions (FAQ)
Q: What GST rate do contractors charge in India? Most contractors charge 18% GST on their services. Civil construction for residential projects is 12%. Government infrastructure projects may attract 12% as well. Always verify the specific rate for your work type with a CA, especially for large projects.
Q: What SAC code should a civil contractor use? For residential construction — 995411 at 12% GST. For commercial construction — 995412 at 18% GST. For roads and infrastructure — 995431 at 12% GST. GST Maker's AI Magic Fill suggests the correct code as you type your service description.
Q: How does a contractor handle GST when working in a different state? If your business is registered in one state and the project is in a different state, you charge IGST instead of CGST + SGST. GST Maker detects the customer's state automatically and applies the correct GST type.
Q: Can a contractor claim ITC on materials purchased for a project? ITC on materials used in works contracts is blocked under Section 17(5) of the CGST Act for most construction contractors. However, if you are a contractor supplying works contract services to another contractor (sub-contracting chain), ITC may be available. Always consult your CA for specific ITC eligibility on your projects.
Q: How should a contractor bill for advance payments? Use a proforma invoice for the advance amount. Once the work reaches the agreed milestone, issue a tax invoice for the amount due. GST Maker lets you convert a proforma to a tax invoice with one click.
Q: Is GST Maker free for contractors? Yes. All core billing features — tax invoices, proforma invoices, quotations, expense tracking, client management, and GST reporting — are free on GST Maker's free plan.
Q: Do sub-contractors need to charge GST? Yes. If a sub-contractor's annual turnover exceeds the GST threshold (₹20 lakhs for services), they must register for GST and charge it on their invoices. The main contractor can claim ITC on the sub-contractor's GST invoice subject to works contract ITC rules.
Run Your Contracting Business. Let GST Maker Handle the Billing.
You got into contracting to build things, install systems, and deliver projects — not to spend your evenings figuring out HSN codes and GST calculations.
GST Maker gives every contractor in India professional, AI-powered, GST-compliant billing — completely free. Create invoices on your phone from the site, share them on WhatsApp, and have your GSTR-1 data ready at month end without any extra effort.
No credit card. No training needed. Your first contractor invoice is ready in 60 seconds.
