Deposit and Milestone Invoices: A Worked Project Workflow

Agree on the billing events before the first invoice

Define the deliverable, price, approval process and event that makes each installment billable. “Second payment halfway through” is difficult to administer if the client and supplier disagree about what halfway means. “Second payment after approval of the two page-layout concepts” gives both parties something observable.

Record who approves the milestone, how approval is given, when payment is due and what happens if client feedback delays the work. These are operational questions to resolve in your agreement, not clauses this article can make enforceable for every jurisdiction. Check local rules before using cancellation charges, automatic acceptance or work-suspension terms.

Worked example: a 3,000 fixed-price project

The following fictional design project uses a 30/40/30 schedule. It is an arithmetic example, not a recommended deposit rate. Tax is excluded solely to keep the allocation visible; determine any tax obligations separately.

One project, three distinct billing stages

Stage	Trigger	Amount	Reference
Initial payment	Agreed booking / start condition	900.00	INV-2026-021
Design milestone	Named concept approval	1,200.00	INV-2026-022
Final milestone	Agreed delivery condition	900.00	INV-2026-023
Total	Full agreed scope	3,000.00	Quote Q-2026-014

Each invoice describes only its allocated stage and cross-references the quote or agreement. Keep a project-level schedule showing all three so the client can see that the amounts total the agreed price. If the first two stages are paid, the last stage is 900.00—not a new 3,000.00 charge.

Do not mix two allocation methods

Some businesses invoice separate stages. Others issue a full-value invoice and allocate payments against it. The correct documentation can depend on the transaction and tax rules. Pick a method with your accountant where needed, then use it consistently.

The common error is issuing three stage invoices totaling 3,000.00 and also issuing an uncancelled full-value invoice for 3,000.00. Your records now appear to bill 6,000.00. A summary of project activity should be clearly identified as a statement or summary, not another demand for the full price.

A deposit payment is not automatically a discount. A discount reduces the charge; a payment settles part of a charge. Reclassifying one as the other can distort the invoice and tax calculation. Use the partial-payment guide to distinguish money received from adjustments.

Create the documents with SunnyBill

1. Prepare the agreed scope in the quotation generator. Keep the accepted version and approval separately.
2. Create each stage in the invoice generator, with its own number, service description, due date and project reference.
3. Export and inspect the PDF. The visible amount due must match the stage actually being billed.
4. Record the payment date and bank reference in your own register. SunnyBill is a browser document tool, not a shared accounting ledger.
5. Before the final stage, reconcile all issued invoices, valid credits and allocated payments.

A proforma can communicate proposed charges, but it is not a substitute for every legally required invoice. Do not use a receipt labeled paid to request an unpaid deposit. See the document comparison when choosing the document type.

Handle a changed scope explicitly

Suppose the client approves an additional 240.00 task after the second milestone. Record that approval and either issue a distinct additional-work invoice or clearly include the approved addition in the final stage, as your records and local rules permit. Do not quietly change the original quote or a previously issued invoice.

If work is cancelled, identify what was supplied, what the agreement permits and what local law requires. A refund, retained advance and price reduction are different outcomes. Use the correction workflow rather than deleting the payment history.

Tax timing is jurisdiction-specific

For UK VAT, HMRC’s advance-payment guidance explains that an invoice or payment can create a tax point before delivery. Returnable security deposits and particular schemes have different treatment. This is not a universal rule for all countries or all deposits.

Use the project billing checklist to document the schedule. Keep local tax advice separate from the arithmetic: a neat 30/40/30 split does not determine when revenue or tax must be recognized.