Milestone-based billing ties payment to specific project stages, which requires a slightly different invoicing structure than hourly or single lump-sum billing.
Define milestones clearly upfront
Before work begins, agree on specific, objectively identifiable milestones (e.g., 'wireframes approved,' 'first draft delivered') tied to a percentage or fixed amount of the total project fee.
Invoice immediately upon milestone completion
Rather than waiting until the end of the project, invoice each milestone as soon as it's reached and (if required) approved by the client.
Reference the milestone clearly on each invoice
Label each invoice with the specific milestone it corresponds to, and note what percentage of the total project this represents.
Clarify approval requirements
If a milestone requires client sign-off before invoicing, make this process clear from the start to avoid disputes about whether a stage was truly 'complete.'
Track overall project progress
Keep a simple running record showing which milestones have been invoiced and paid, especially for longer projects with several stages.
Why this structure works well
Milestone billing keeps cash flow steady throughout a project and gives both freelancer and client clear checkpoints to assess progress against payment.