Project-Based Invoice Template and Example

Consider a $12,000 website build paid in three stages. Each stage needs its own invoice, and each one should show the client where the project stands: what the contract is worth, what has been billed, what this invoice covers and what is left. A project invoice template is built for exactly that. It bills a defined job, or one phase of it, instead of a period of time, and keeps a running total across the whole project.

This guide covers the fields a project-based invoice needs, the common billing structures, a filled example with the billed-to-date math, and the mistakes that slow approval on project work.

What makes a project invoice different

A standard invoice lists items and a total. A project invoice adds context that ties each bill to a larger agreement:

• Project name and number, plus the client's PO or budget code
• Contract value, including approved change orders
• Stage or milestone being billed in this invoice
• Billed to date (previous invoices) and remaining balance
• Deliverables completed for this stage, so the approver can check them off

The basics still apply: a unique invoice number, both parties' details, dates, a description, any tax, and the total. The UK government's list of what invoices must include is a useful reference point wherever you work.

Ways to bill a project

Single invoice on completion

Best for short projects of a few weeks. Simple, but you finance the whole job until the client pays. A flat fee invoice is often all you need here.

Deposit plus balance

A deposit (often 25 to 50 percent) before work starts and the balance on delivery. See our guide to deposit invoices for how to word the first bill.

Milestone billing

Fixed amounts tied to deliverables, such as design approval or launch. This is the most common structure for creative, software and consulting projects. Our explainer on how milestone billing works includes sample schedules.

Progress billing

Billing a percentage of the contract based on how much work is complete, usually monthly. Common in construction and engineering. Read more in progress billing: percent complete vs milestone.

Project invoice example (stage 2 of 3)

A web studio agreed a $12,000 website build in three milestones: 30 percent on signing, 40 percent on design approval, 30 percent on launch. The client later approved a $900 change order for an extra booking page, billed with stage 2.

Project summary	Amount
Original contract value (Project WEB-214, PO 7731)	$12,000.00
Approved change order CO-01 (booking page, approved 20 Oct 2026)	$900.00
Revised contract value	$12,900.00
Previously billed: Stage 1, Invoice 2026-088 (paid)	$3,600.00

This invoice	Amount
Stage 2: design approval, 40% of $12,000 (homepage and 6 inner page designs approved 6 Nov 2026)	$4,800.00
Change order CO-01: booking page design and build	$900.00
Total this invoice (Invoice 2026-104), due 27 Nov 2026	$5,700.00
Remaining after this invoice (Stage 3, 30%)	$3,600.00

The math: stage 1 was $12,000 x 30% = $3,600. Stage 2 is $12,000 x 40% = $4,800, plus the $900 change order, for $5,700. Billed to date after this invoice: $3,600 + $5,700 = $9,300. Remaining: $12,900 - $9,300 = $3,600, which matches stage 3 ($12,000 x 30%). When the remaining balance lines up with the schedule, the client can approve quickly. Our guide on how to calculate an invoice total covers the order of discounts, tax and deductions if your project adds those.

How to build a project invoice template, step by step

1. Set up the header with your details, the client's details, invoice number, dates, and the project name, number and PO.
2. Add a project summary block: original value, approved changes, revised value, previously billed.
3. Add the current billing lines: the stage or percentage, with deliverables named, plus any change orders.
4. Calculate tax on this invoice's amount if you are registered.
5. Show the remaining balance after this invoice.
6. Attach evidence where useful: approval emails, a sign-off, or a work completion certificate for the final stage.
7. Keep the template per project, so each new stage invoice starts from the latest billed-to-date figures.

Variations by industry

• Construction: progress billing with retainage withheld, often using a schedule of values. Show retainage as a separate deduction.
• Software and web: milestones tied to sprints, approvals or launch, with change requests priced separately.
• Consulting: phase fees (discovery, analysis, recommendations) with expenses billed at cost.
• Events and creative: deposit to book the date, a second payment before delivery, balance after.

Setting up a billing schedule before the project starts

The project invoice is only as clear as the billing schedule behind it. Put the schedule in the contract or proposal, with each stage defined by something both sides can verify. A good schedule answers four questions for every stage:

• What triggers the invoice? A date, a deliverable, a written approval, or percent complete.
• How much is billed? A percentage of the contract or a fixed amount.
• What evidence is needed? An approval email, a signed sign-off sheet, a site inspection.
• What are the payment terms? For example, each stage invoice is due in 14 days.

Front-loading a little helps cash flow. A deposit of 25 to 30 percent covers your early costs, and keeping the final stage at 20 to 30 percent gives the client confidence without leaving you financing most of the job.

Expenses and pass-through costs on project invoices

Many projects include costs on top of the fee: travel, stock images, software licences, printing, subcontractors. Decide in the contract whether these are included in the fixed price or billed separately. If they are billed separately, list them on the stage invoice in their own section, with receipts, and say whether you add a handling fee. Keeping fees and expenses separate also makes the remaining-balance calculation simpler, because the contract value usually refers to fees only.

Project invoices for time-and-materials work

Not every project has a fixed price. On time-and-materials projects, a project invoice still uses the same summary block, but the "contract value" becomes an approved budget or estimate. Each invoice shows hours and costs for the period, the total billed to date, and the budget remaining. When billed-to-date reaches about 80 percent of the budget, tell the client in writing, so a revised estimate can be agreed before the budget runs out rather than after.

Closing out the project

The final invoice should make it obvious that the project is complete. Bill the last stage, release any retention, and show that billed-to-date now equals the revised contract value. Add a short line such as "Final invoice: project complete, no further fees due under Project WEB-214". If the client still owes earlier invoices, list them with their amounts so everything outstanding is in one place.

Retention and holdbacks

Some clients, especially in construction and engineering, hold back a percentage of each payment until the project is finished and any defects are fixed. If your contract includes retention, show it openly on each project invoice. For example, a $20,000 stage invoice with 5 percent retention reads: stage amount $20,000, less retention at 5 percent ($1,000), amount due $19,000. Track the total retention held across all invoices, and bill its release as a separate line on the final invoice, or after the defects period ends, as the contract says. Our guide to construction invoices with retainage covers this in more detail.

Sending stage invoices so they get approved

Project invoices often go through more than one approver: the project lead confirms the work is done, then finance checks the budget code and pays. Make both jobs easy. Address the email to your project contact with finance copied, put the project number, stage and invoice number in the subject line, and attach the evidence for the stage, such as the approval email. One clear message with everything attached gets processed faster than an invoice followed by a separate thread of supporting documents.

Common project invoicing mistakes

• No running total. Without billed-to-date figures, clients have to rebuild the history themselves, and approval slows.
• Billing a milestone before it is met. If the client has not approved the design, do not bill the design milestone.
• Unapproved changes. Bill only change orders the client has agreed in writing.
• Missing PO or project number. Larger organisations often cannot pay an invoice that does not reference one.
• Totals that do not reconcile with the contract value once all stages are added up.

Create your project invoice

You can set up a project invoice with stage lines, change orders and a remaining-balance note in our invoice generator. It is free with no sign-up, and every stage invoice downloads as a tidy PDF you can send straight to the client.