What Is Progress Billing? A Practical Guide

Progress billing is a way to invoice a project in stages instead of waiting until the entire job is complete. Each invoice requests payment for an agreed portion of work, milestone or percentage completed, while showing what has already been billed and what remains.

It is common in construction, consulting, design, manufacturing and other projects that run for weeks or months. The method supports cash flow and gives the customer visibility, but only when scope, progress and previous payments are documented consistently.

How progress billing works

A progress-billing arrangement starts with an agreed contract value or project scope. The parties then define when invoices can be issued. Triggers might be monthly dates, completed milestones, measured quantities or an approved percentage of completion.

Each progress invoice usually shows:

• Original contract or quoted value
• Approved changes
• Revised project value
• Work completed to date
• Amount billed previously
• Amount claimed this period
• Deposits or retention
• Tax and current amount due
• Remaining unbilled value

InvoiceSonic's progress billing template helps present those figures in a repeatable format.

Progress billing example

Imagine a $50,000 project billed in four stages:

1. 20% deposit when the work is booked: $10,000
2. 30% after the first milestone: $15,000
3. 30% after the second milestone: $15,000
4. 20% on completion: $10,000

The second invoice should not simply say “$15,000.” It should identify the contract value, deposit already billed, milestone reached, amount due now and value remaining. That running summary lets the customer see that cumulative billing still matches the project.

Progress invoice vs standard invoice

A standard invoice can stand alone for one completed sale. A progress invoice belongs to a sequence. Its meaning depends on the contract, earlier claims and remaining work.

The document therefore needs cumulative information. Without it, a customer may not know whether the current amount is additional, cumulative or a replacement for an earlier invoice.

Use unique invoice numbers for every stage. Do not overwrite the first invoice with the second stage because that removes the transaction history.

Milestone billing vs percentage billing

Milestone billing links payment to defined events: plans approved, materials delivered, installation complete or final handover. It works well when progress can be demonstrated by an outcome.

Percentage billing links payment to the proportion of work completed. It can suit projects where work advances continuously, but the measurement method should be agreed. A bare “60% complete” statement is weaker than a schedule showing the value of each component and its completion.

Some projects use both. A contract may require a deposit, monthly percentage claims and a final milestone payment.

Deposits and progress billing

A deposit secures the booking, funds initial costs or confirms the customer's commitment. It should be identified clearly and later credited against the total where that is the agreement.

Use a deposit invoice for the initial request, then carry the deposit into the progress-billing summary. The guide to invoicing a deposit and final payment shows how to prevent the deposit from being charged twice.

Build a schedule of values

For larger work, divide the project into components with an assigned value. This is often called a schedule of values.

A renovation might separate demolition, framing, electrical, plumbing, finishes and handover. A software project might separate discovery, design, development, testing and launch. The assigned values should add up to the agreed project total.

On each billing date, record progress against those components. This creates a defensible calculation and makes changes easier to trace.

Record approved variations

Projects change. A customer may request additional work, remove an item or alter specifications. Do not quietly adjust the original contract value.

Record the variation, its approval and price, then show how it changes the revised contract total. Distinguish approved changes from proposed changes that have not yet been authorised.

If a variation affects the current invoice, describe it separately. The customer should be able to reconcile the invoice with the written approval.

Calculate the current amount due

A common structure is:

1. Calculate the value of work completed to date.
2. Subtract amounts billed previously.
3. Apply any agreed retention.
4. Add relevant tax.
5. Credit payments or deposits where required.
6. Arrive at the current amount due.

Check whether percentages apply to the original contract, revised contract or individual schedule items. Use the same basis throughout the project.

Retention and holdbacks

Some contracts allow the customer to retain part of each progress payment until completion or the end of a defects period. If retention applies, show the gross earned amount, retention withheld and net amount currently due.

Do not describe retention as an unexplained discount. Track the accumulated retained amount so the final release can be invoiced and reconciled correctly.

Rules for retention and progress claims vary by contract and location. For material projects, confirm the required wording, timing and supporting evidence with an appropriate professional.

Supporting evidence

Customers may need evidence before approving a claim. Useful support can include milestone sign-off, timesheets, delivery records, photographs, quantity measurements or a short progress report.

Reference the supporting document from the invoice rather than sending an unexplained attachment. Keep the evidence proportionate: the aim is to make approval easy, not bury the customer in paperwork.

Payment terms and due dates

State when each progress invoice is due and how to pay. Align the billing dates with the customer's approval cycle so invoices do not sit waiting for a monthly meeting that has already passed.

For projects dependent on timely progress payments, explain what happens when a payment is late. Do not introduce new late-fee or suspension terms after the project begins; they should come from the agreed contract.

Tracking progress invoices

Track every stage separately by invoice number, issue date, due date, amount and status. A project can have one paid stage, one current stage and one disputed stage at the same time.

Match each incoming payment to the correct invoice. If the customer combines stages in one transfer, record the allocation so no settled invoice remains incorrectly overdue.

Common mistakes

Common errors include showing only the current charge, confusing cumulative and current amounts, failing to credit a deposit, billing unapproved changes and altering earlier invoices instead of issuing new records.

Another mistake is using percentages that do not match observable progress. A schedule of values or milestone record makes the calculation easier to explain.

Frequently asked questions

Is progress billing only for construction?

No. It can suit any longer project with measurable stages, including consulting, creative work, manufacturing and software delivery.

Is a progress invoice a partial invoice?

It requests part of a larger project value, but it should also show the cumulative project position. A generic partial invoice may not provide that context.

How often should progress invoices be sent?

Use the schedule agreed with the customer: milestones, monthly dates or another measurable trigger. Avoid billing at unpredictable intervals.

What happens on the final invoice?

Show the completed project value, all approved changes, prior billings, retention or credits and the final balance. The cumulative total should reconcile to the agreement.

Progress billing turns a long project into understandable payment stages. Define the measurement method, preserve the cumulative history and make every current amount traceable to work the customer can recognise.