Progress Billing: How to Invoice a Project in Stages

Progress Billing: How to Invoice a Project in Stages

Progress billing lets a business request payment as an agreed part of a project is completed, instead of waiting until the whole job is finished. It can make a long project easier to fund and give the client a clear record of what each payment covers. The important word is agreed. The invoice schedule should come from the contract or proposal, not from a percentage chosen after the work begins.

This guide covers ordinary staged invoices for service and project work. Construction contracts may require a formal payment application with a schedule of values and approval process. An ordinary invoice is not a substitute for that package. If your project has those requirements, use the formal documents named in your contract. Our construction invoice guide covers the separate invoice fields.

What progress billing means

Under progress billing, the full project price is divided into billing events. A billing event may be a completed milestone, a percentage of work verified at a regular date, or a defined quantity of work delivered. Each invoice requests only the amount due for its period or stage. The invoices together should reconcile to the agreed price, including any approved changes.

For example, a website project priced at $12,000 might be billed 30 percent after discovery and planning, 40 percent after an approved working build, and 30 percent at final handoff. The first invoice is for $3,600, the second for $4,800, and the last for $3,600. The percentages add to 100, and the three invoice amounts add to $12,000.

A progress invoice differs from a recurring invoice. Recurring billing charges on a repeating schedule, often for ongoing access or service. Progress billing is tied to a specific project's completion or contract-defined billing period. It also differs from a deposit invoice, which may request money before work is done. The deposit's treatment should be stated in the agreement and reflected when later amounts are billed. For more on that distinction, see our deposit invoice guide.

Choose a billing schedule before work starts

Discuss the schedule while setting scope and price. State what triggers each invoice, who confirms the work, what documents the client expects, and when payment becomes due. A phrase such as “bill halfway through” is hard to apply if the project changes. “Bill 40 percent when the client approves the working prototype” is easier to verify, provided the agreement also says how approval is recorded.

For a percentage-of-completion arrangement, define how completion is measured. A consulting engagement might use approved deliverables or hours against a capped scope. A construction job might use a schedule of values that assigns an agreed amount to each work item. Do not assume that spending 60 percent of your budget means 60 percent of the project is billable. Cost incurred and work accepted are different measures.

Decide how scope changes will be authorized. If the client adds a new deliverable, document the revised price and billing treatment before adding it to a progress invoice. Otherwise, the client may see a higher amount than the original agreement supports.

Calculate the current invoice without double billing

A simple milestone schedule can be calculated from the contract amount: contract price multiplied by the percentage assigned to the completed milestone. For cumulative progress billing, calculate the value of work completed to date, then subtract amounts already invoiced for that same work. This is a calculation of the new claim, not a calculation of cash collected.

Project stage	Share of $12,000 contract	Current invoice	Cumulative invoiced
Discovery and plan	30%	$3,600	$3,600
Working build approved	40%	$4,800	$8,400
Final handoff	30%	$3,600	$12,000

At the second stage, $8,400 of the contract has been billed cumulatively. Subtract the $3,600 first-stage invoice to get the $4,800 now due for stage two. If the first invoice remains unpaid, it is still a separate receivable. Do not quietly roll it into the stage-two charge or label the $8,400 cumulative figure as the new amount due. Send a statement or payment reminder separately if you need to show outstanding balances.

Keep a small ledger for each project with the contract price, approved changes, billing stages, invoice numbers, amounts invoiced, payments received and remaining unbilled amount. This is especially important when an invoice has been corrected or a milestone has changed. The total invoiced should never exceed the agreed amount unless an approved change explains the difference.

What to show on a progress invoice

Use the normal invoice basics: your business and client details, a unique invoice number, issue date, due date, currency, line items and payment instructions. Add enough project context for someone who did not manage the work to understand the request. Useful details include the project name, contract or purchase order reference, stage name, billing period, and a short description of the completed work.

The line item should identify this stage rather than restate the entire project as though it were newly due. For example, “Website build, approved prototype milestone, 40 percent of $12,000 contract” communicates both the work and the math. If the client requires supporting evidence, attach the approval email, timesheet, delivery record or signed acceptance document through your normal communication channel.

You can create a PDF progress invoice with ToolNimbly by entering the current stage as a line item and adding the project reference in the description or notes. The tool calculates line totals and produces a printable document. It does not verify milestones, remember earlier invoices across devices, send the invoice, or maintain a project billing ledger for you.

Handle taxes, deposits and changes carefully

A staged billing schedule does not automatically determine when tax applies. Sales tax and VAT treatment depend on the transaction and jurisdiction. Use the correct tax instructions for your business, and check with an accountant when a deposit, partial payment or cross-border project creates uncertainty. Do not copy a rate from an earlier invoice without confirming it still applies.

If the client paid a deposit, check whether the agreement treats it as an advance against a later stage or as a separate amount. Make the credit visible so the client can see how the remaining balance was reached. If a change order increases the project price, keep the original price and approved change identifiable in your records. Do not hide an added charge inside a vague “remaining work” line.

Common problems to catch before sending

• Unclear trigger: The invoice says “phase two” but the agreement does not define what phase two includes. Name the deliverable or period.
• Duplicate work: A task appears on two invoices. Compare line items against the billing ledger before sending.
• Wrong cumulative amount: A summary of work to date is presented as the new amount due. Separate cumulative context from this invoice's charge.
• Unapproved extras: Added work is billed before a change is agreed. Confirm scope and price first.
• Missing reference: The client's accounts-payable team cannot match the invoice to a project or purchase order. Include the identifier they requested.

Progress billing works best when the billing plan is established early, the evidence for each stage is easy to find, and each invoice makes its own amount due unmistakable. Before sending, reconcile this invoice with the contract and earlier invoices, then keep a copy of the PDF and the supporting approval in the project record.