A project deposit, a retainer and a milestone payment solve different risks. Use a deposit to confirm one project and fund its start, a retainer to reserve recurring access or capacity, and milestone payments to divide a larger project into accepted stages. The best structure follows the work—not whichever term sounds most professional.
This guide is for freelancers, agencies, consultants and service businesses choosing how to bill a new engagement. It includes a decision matrix and a worked €6,000 example you can adapt before creating an invoice or payment request.
Deposit, Retainer and Milestone at a Glance
| Structure | Best for | Customer is paying for | Main risk it controls |
|---|---|---|---|
| Project deposit | A defined project with a future start | Commitment and the agreed first portion | Starting work without a committed client |
| Retainer | Ongoing access, capacity or recurring service | A repeated period or reserved availability | Unpredictable recurring workload and revenue |
| Milestone payments | A larger project with reviewable stages | Completed or approved phases | Too much unpaid work accumulating at once |
A deposit can also be the first milestone, but say so explicitly. A retainer is not simply any advance payment: it should define the period, capacity, service level, rollover and cancellation rules.
Choose With Five Questions
- Does the engagement have one defined finish? A project deposit or milestones usually fit better than a retainer.
- Can the work be divided into outcomes the client can review? Use milestones when each stage has a meaningful acceptance point.
- Is the client buying recurring access or reserved capacity? That points to a retainer.
- Would one unpaid final invoice expose too much work? Divide the amount before that exposure becomes uncomfortable.
- Can both sides explain what triggers each payment? If not, the schedule is not ready to send.
Do not choose a percentage by habit. First map the work, third-party costs, cancellation exposure and approval points. Then allocate payments to those risks.
When a Project Deposit Works Best
A deposit fits a defined engagement where you reserve a start date, reject other work or incur early costs. The agreement should say whether the amount is refundable, what happens if either party postpones, and how it is credited toward the total.
For example, a photographer may collect a booking deposit before reserving a date. A designer may collect an initial amount after the scope is signed and before discovery begins. The deposit should connect to the same project reference used on later invoices.
Avoid calling every upfront amount “non-refundable.” Consumer, cancellation and unfair-contract rules vary by jurisdiction. State the commercial reason and have material terms reviewed where you sell.
When a Retainer Is Better
Use a retainer when the relationship repeats and the client buys defined access, output or capacity during each period. Examples include monthly bookkeeping, a fixed content package, a support allowance or reserved advisory hours.
A useful retainer specifies:
- what is included each period;
- response or scheduling expectations;
- whether unused capacity rolls over;
- how extra work is approved and priced;
- renewal, notice and cancellation dates;
- what happens to open work when the retainer ends.
If the client only needs one project, recurring billing can create unnecessary cancellation and scope questions. Use a project schedule instead.
When Milestones Reduce Risk
Milestones suit work with distinct, reviewable phases: discovery, concept, prototype, implementation, launch or handoff. Each payment needs an objective trigger such as “approved wireframes” or “staging site ready for acceptance,” not a vague date detached from progress.
Do not make the last milestone so large that most work remains unpaid until final delivery. Do not make the first so large that the client carries nearly all performance risk. The schedule should keep both parties invested.
Worked Example: A €6,000 Website
| Trigger | Share | Amount | What the client can verify |
|---|---|---|---|
| Signed scope and reserved start | 30% | €1,800 | Start date, plan and discovery booked |
| Design approval | 30% | €1,800 | Agreed screens and documented revisions |
| Staging acceptance | 30% | €1,800 | Functional build tested against scope |
| Production handoff | 10% | €600 | Final files, access and handover checklist |
This is an example, not a universal formula. If licenses or subcontractors must be paid early, the initial amount may need to cover those costs. If procurement permits only Net 30 after acceptance, negotiate a smaller financed exposure or a different stage before work starts.
Put the Schedule in Writing
For every payment, record the amount, invoice date, due date, trigger, deliverable, review window and consequence of delay. Use one project reference across the proposal, agreement, invoices, payment records and handoff.
Example wording:
> The €1,800 design milestone becomes due after the client approves the listed desktop and mobile screens in writing. Approval starts the build phase. Requests outside the signed scope require a written change and may alter the schedule.
Adapt contract language to the engagement and jurisdiction. Operational clarity is not a substitute for legal advice.
Build the Collection Workflow
- Agree scope and payment triggers before sending requests.
- Create the customer and one recognizable project reference.
- Send the deposit or first milestone with a clear description and due date.
- Confirm completed payment in your own dashboard—not from a screenshot.
- Record written acceptance before invoicing the next stage.
- Pause at the agreed boundary if payment or approval is overdue.
- Reconcile the final payment before releasing production files when the agreement requires it.
PayRequest can keep customers, invoices, payment requests and provider records in one workflow. Use invoicing for customer-specific amounts, payment links for a standard upfront offer, or subscriptions when a genuine retainer renews.
Write the stages first. Then create a free PayRequest account and build the matching flow. Every standard feature is included on Free; PayRequest charges 2% per successful payment, capped at €25 per transaction, plus connected-provider fees.