Evrenus Fırat Polat · ·
For a project that takes weeks or months, invoicing only once, at the very end, means carrying the full cost of your time and materials until the last possible moment. Progress invoicing splits the total into payments tied to milestones, so cash comes in as the work does.
How to split the milestones
There is no single right way to divide a project, but a few common patterns work well:
- By phase. Design, then build, then finish, each phase invoiced on completion. Natural for work with clear, sequential stages.
- By percentage complete. 25% at kickoff, 25% at the halfway mark, 50% on delivery. Useful when the work does not break cleanly into distinct phases but progress is still trackable.
- By calendar. Monthly invoicing for a project of known duration, regardless of exactly what has been completed that month. Common for long, ongoing work rather than a project with a hard endpoint.
Whichever pattern you choose, agree on it, and the amounts tied to each milestone, before work starts. The best place is the original quote. See estimate to paid invoice for how the quote flows into billing.
Worked example
A contractor agrees to renovate a kitchen for $24,000, excluding sales tax. The agreed schedule:
| Milestone | Share | Amount |
|---|---|---|
| Deposit at signing | 25% | $6,000 |
| Demolition and rough-in complete | 25% | $6,000 |
| Cabinets and counters installed | 30% | $7,200 |
| Final completion and sign-off | 20% | $4,800 |
| Total | 100% | $24,000 |
Midway, the client asks for a better countertop, adding $1,500. The contractor documents it as a change order and adds it to the third milestone invoice as its own line:
- Cabinets and counters (agreed): $7,200
- Change order #1, upgraded countertop: $1,500
- Invoice total: $8,700
The final invoice then summarizes everything:
- Contract value: $24,000 + change order $1,500 = $25,500
- Invoiced to date: $6,000 + $6,000 + $8,700 = $20,700
- Final invoice: $25,500 − $20,700 = $4,800
The numbers close cleanly because each invoice states what is billed and what remains. The first payment can be handled as in invoice deposits. If tax applies, it is calculated on each invoice according to your local rules, so confirm the treatment with an accountant.
What each progress invoice should show
Every invoice in the sequence should make clear which milestone it covers, the amount for that milestone, and ideally the total project value and what has been invoiced so far. A client should not have to dig through old invoices to know where the project stands financially. Each new one should make that obvious on its own. A simple table at the bottom works:
- Contract total
- Previously invoiced
- This invoice
- Remaining
Use the invoice generator with a clear description per line, and the project invoice calculator to check percentages.
Step-by-step setup
- Define the scope clearly in the quote.
- Choose milestones that are easy to verify, such as "drawings approved," not "mostly done."
- Set the share and amount for each, and the payment terms. See setting payment terms.
- Get the schedule accepted in writing.
- When a milestone is reached, send the invoice quickly, with any proof needed (photos, deliverables, sign-off).
- Track each one using invoice statuses.
- Close with a final invoice that ties everything together.
Handle scope changes explicitly
Long projects are the ones most likely to have scope shift partway through. When that happens, do not silently fold the change into the next progress invoice. Note it clearly. If the change is significant, treat it as its own line item or even its own invoice, so it does not get lost inside a milestone payment the client was already expecting.
Common mistakes
- Front-loading nothing. Without a deposit, you fund the project's start yourself.
- Back-loading too much. If 80% is due at the end, your exposure stays high. Aim for payments that at least cover your costs to date.
- Vague milestones. "50% complete" invites dispute. Tie payments to something visible.
- Forgetting retainage. In some industries, clients hold back a share until completion. Ask about it up front.
- Not pausing on non-payment. If a milestone invoice is late, agree in the contract that work can pause. Then follow the steps in overdue invoices.
Reconcile at the end
The final invoice should tie everything together: total project value, total already invoiced across all milestones, and a final balance due, if any. This closing summary is what makes progress invoicing feel organized rather than like a series of loosely connected bills.
FAQ
Is progress invoicing the same as a deposit?
A deposit is one kind of staged payment. Progress invoicing covers the whole sequence, including the deposit and later milestones.
How many milestones should I use?
Most small projects work with three to five. More than that adds admin work without much benefit.
Should I invoice for work not yet delivered?
Deposits and prepayment milestones are common, but rules on when revenue counts differ by country and accounting method. Ask your accountant.
What if the client disputes a milestone?
Discuss the evidence of completion. If the dispute is about a part only, consider invoicing the undisputed portion. See invoice disputes.
Splitting a big project into staged payments is not only about your own cash flow. A client who sees steady, itemized progress billing tends to trust that the project is on track, too.