What project-based billing is
Project-based billing is invoicing against a project and what it consumed — not against a product SKU. The customer is not buying 40 units off a price list; they are buying a fabricated structure, an erected plant, a machined job-work lot, a delivered scope. The bill therefore draws its lines from the project's resources — labour categories, machine hours, materials, milestones — values them at agreed rates, applies GST, and produces a compliant bill with amount in words, exactly as a product invoice would.
The deep similarity with product billing is worth seeing clearly: it is the same GST billing engine pointed at a different source document. A product invoice is raised against a dispatch; a project bill is raised against a project. Everything downstream — tax computation, printing, receipts and advance adjustment, posting to Tally — behaves the same. What changes is what the bill reconciles against, and that is what this guide is really about.
The bill of resources — the project's price list
The bill of resources is the priced plan of what the project will consume: labour categories with day or hour rates, machines with usage rates, materials with quantities and rates, services and subcontracted items. It does for a project what the item master does for product billing — it is the agreed basis every bill draws from, and the reference every billed line can be checked against.
Billing against it has two audiences. The client's engineers and accounts team scrutinise project bills line by line; a bill whose lines tie to the agreed resource schedule at the agreed rates survives scrutiny, while a lump-sum "for work done — ₹18,40,000" invites disputes and deductions. And internally, resource-wise billing is what tells you whether the project is recovering its consumption — which resources are billed out, which are being consumed unbilled, and where the contract is drifting from the plan.
Bill types — milestone, progress, resource consumption
Projects bill in patterns, and a billing system should represent them as explicit bill types rather than free-form documents:
| Bill type | Billed when | Typical use |
|---|---|---|
| Milestone bill | A defined stage completes — mobilisation, foundation, erection, commissioning | Construction and EPC contracts with a payment schedule |
| Progress bill | Periodically, for measured work done or percentage completion | Long-running contracts billed monthly on measurement |
| Resource-consumption bill | Resources are consumed — labour days, machine hours, materials | Job-work, hire, time-and-material and service contracts |
| Final / closure bill | Scope completes; reconciles everything billed to the contract value | Project closure, retention release |
Typing the bill matters for the same reason document types matter everywhere in billing: a typed bill knows its own behaviour and its own reporting. Milestone bills reconcile against the payment schedule; progress bills against cumulative measurement; resource bills against consumption records. At project close, the reconciliation — everything billed, by type, against contract value — is a report, not an archaeology exercise.
GST on project bills
A project bill is a taxable supply like any other, and it carries GST computed the same way a product invoice does — with two project-specific wrinkles:
- Service classification. Project bills are usually services — SAC-coded, with works-contract or job-work treatment depending on the nature of the contract. The applicable rate and treatment follow from that classification, not from a goods HSN.
- Place of supply. The CGST/SGST vs IGST split still applies, decided by place-of-supply rules — which for works on immovable property generally follow the site. An out-of-state contractor billing a project site follows these rules, not their home state's defaults.
Works-contract and job-work GST have genuinely specific rules — rates, input-credit restrictions, and classification questions that depend on the contract. The right pattern is the one used throughout this cluster: configure the treatment once with your CA, attach it to the project's bill types, and let every bill inherit it, with rounding and amount in words applied automatically at the end.
Still assembling project bills in Excel every month?
See a project bill raised against a bill of resources — typed, GST-applied, printed with amount in words, advance adjusted — in a 30-minute demo on one of your own contracts.
Advances, retention and the running account
Project money moves differently from product money, and three mechanics from the receipts guide become central:
Mobilisation advances. Contracts commonly pay an advance before work starts. That advance sits on account against the project's client and is adjusted progressively against milestone or progress bills — often a fixed percentage per bill — until recovered. Unadjusted mobilisation advances are one of the classic ways project firms lose track of their true position.
Retention. Clients typically hold back a percentage of each bill until completion or the defect-liability period ends. Each bill should show the retention deducted, and the accumulated retention should be visible as receivable-later money — not forgotten until someone wonders why collections never match billing.
The running account. Across a long project, the client's position is a living statement: bills raised by type, advances adjusted, retention held, payments received, balance due. Because project bills, receipts and advances live on one linked chain in a billing system, that statement is a report — and the same outstanding and follow-up discipline that chases product invoices chases progress bills.
Product invoices and project bills, side by side
Many firms are not one thing. A fabricator sells standard components to dealers and executes turnkey contracts; an equipment maker sells machines and bills erection and commissioning as projects. Running the two billing modes in separate tools splits the party master, the tax configuration and the accounts sync — and guarantees reconciliation pain. Running them on one platform means:
- One party master — a client can hold product invoices and project bills, with one consolidated outstanding.
- One tax configuration — goods rates from the HSN map, service treatment on project bill types, both feeding the same returns data.
- One accounts sync — product invoices and project bills both post to Tally as sales vouchers with GST, receipts as receipt vouchers, nothing re-keyed.
How Fast Billing Software bills projects
Project billing is a native mode of Fast Billing Software — the Project & Resource Billing module. A bill is raised against a project and its bill of resources: the bill header carries the project, resource lines carry labour, machine and material consumption at agreed rates, and a bill type classifies it as milestone, progress or resource billing. GST and charges apply from the same tax configuration as product invoicing, and the printable bill carries the full compliant layout with amount in words in Indian numbering.
Around the bill, the rest of the platform behaves as this cluster describes: mobilisation advances record and adjust through receipt entry, corrections flow through credit and debit notes, and every bill posts to Tally with GST on the correct ledgers. For firms running the full Fast Suite, the project and its bill of resources can come from Fast Project Management — but the billing mode also runs on its own, as it does for firms whose entire revenue is project work. See Construction & Project Billing for the industry view.
A ₹2.4 crore contract, billed in eight controlled slices
A contractor wins a ₹2.4 crore fabrication-and-erection contract with a 10% mobilisation advance and 5% retention. The project is set up with its bill of resources — fabrication tonnage, erection crew days, crane hours, consumables. Work bills monthly: each progress bill draws measured tonnage and crew days from the resource plan at contract rates, deducts one-eighth of the advance and 5% retention, applies GST per the works-contract configuration, and prints with amount in words. The client's engineer checks each line against the agreed schedule and clears bills in days, not weeks. At closure, the running account shows eight bills, advance fully adjusted, ₹12 lakh retention receivable on defect-liability expiry — one report, no archaeology.
Frequently asked questions
What is project-based billing?
Invoicing against a project and the resources it consumed — labour, machines, materials, milestones — rather than a product SKU. Each bill draws from the project's bill of resources, applies GST and charges, and prints as a compliant bill with amount in words. Same billing engine as a product invoice; different source document.
What is a bill of resources?
The project's priced resource plan — labour categories, machines, materials and services with units and rates. It plays the role the item master plays in product billing: the agreed basis every bill draws from, and the reference client scrutiny and internal control check against.
How does GST apply to project bills?
Project bills are taxable supplies, usually SAC-coded services with works-contract or job-work treatment depending on the contract, with CGST/SGST or IGST decided by place-of-supply rules. Configure the treatment once with your CA and attach it to the project's bill types.
What is progress billing?
Billing a project in stages — by milestone, percentage completion, or measured work per period. Each progress bill invoices the portion earned from the bill of resources or schedule of values, adjusts advances and retention, and leaves the remainder for future bills.
Can one system run both product invoices and project bills?
Yes — one party master, one tax configuration, one Tally sync. A firm can invoice standard products against dispatches and raise progress bills against projects from the same platform, with a single consolidated outstanding per client.