1. Decide whether the scope is stable enough
Flat rate can make a defined job easier to understand. Unknown conditions, open-ended discovery, or client-selected finishes may need allowances, milestones, or time-and-materials terms instead.
- Can the work be described?
- Are access and site assumptions known?
- Can exclusions and changes be documented?
- Does the agreement support a fixed price?
2. Build the worksheet behind the total
List direct labor, materials, equipment, subcontractors, overhead allocation, contingency, and the margin or fee agreed with the client. Write the unit and quantity behind each assumption even if the client sees one fixed total.
| Cost bucket | Illustrative amount |
|---|---|
| Labor | $2,400 |
| Materials | $1,800 |
| Equipment | $500 |
| Overhead/fee allowance | $700 |
| Illustrative fixed price | $5,400 |
3. Protect the scope and change process
State what is included, excluded, assumed, scheduled, and priced. A change order should identify the approved addition, price, timing, and reference date. Do not fold extra work into an existing line item.
4. Keep the invoice consistent with the agreement
The invoice can show the contract value, milestone or stage claimed, approved changes, amounts previously billed, and remaining balance. Keep the language aligned with the signed scope; a template records the agreement but does not set a correct price.