Guide · 7-minute read
Choose hourly or fixed-fee billing from the work—not habit.
Hourly and fixed-fee projects can live in the same client relationship, but they answer different risk questions. This guide shows how to choose the model, track the delivery work, and keep each invoice legible.
Last updated August 18, 2026
Use hourly billing when the scope is still moving
Hourly billing fits discovery, advisory work, incident response, open-ended maintenance, and any engagement where the client controls the volume of requests. The client pays for actual effort, so the commercial risk of an expanding scope is shared rather than silently absorbed by the service provider.
Make the rate, billing increment, billable categories, and reporting cadence explicit before work begins. Track each entry against the correct client, project, and task; mark internal or goodwill work non-billable while context is fresh. At invoice time, select the eligible entries that belong to the period instead of rebuilding them from memory.
Use a fixed fee when the outcome and boundary are knowable
Fixed fees work when both sides can describe the deliverable, assumptions, revision boundary, and acceptance point. The client gains price certainty; the provider takes delivery risk and keeps the upside from an efficient process. A fixed fee is not an instruction to stop tracking time—it changes what the time is for.
Track fixed-fee effort for delivery health, future estimating, and profitability analysis, but do not turn those hours into hourly invoice charges. Invoice the agreed contract value, or an agreed partial allocation such as a deposit or milestone, and show expenses separately when the agreement allows them.
Keep mixed engagements explicit
A client can have a fixed implementation and hourly support without making the invoice confusing. Use separate projects with separate pricing policies. The fixed project contributes its contract allocation; the hourly project contributes selected time; billable expenses and truly exceptional work remain their own source types.
Do not convert a fixed project into an hourly one because delivery ran long. That rewrites the commercial agreement after the fact. Treat the overrun as information for scope control and future pricing, then agree a new hourly or fixed change request before additional work begins.
How Hoursmith does it
How Hoursmith separates the models
Hoursmith projects are hourly, fixed-fee, or non-billable. Hourly entries may flow into an invoice; fixed-fee and non-billable project time stays delivery-only. A reconciled fixed project exposes its remaining contract value and supports partial allocation without converting effort into an hourly charge.
The invoice builder can combine selected hourly entries, fixed-fee allocations, expenses, and custom lines while preserving each source. Sent invoices freeze the commercial snapshot, and the underlying hourly entries lock against later editing.