Adding a commission percentage to cost does not preserve the target margin. Commission is based on the selling price.
Try this with your own numbersFormula and worked example
Quote = (itemised delivery costs + allocated overhead) ÷ (1 − margin − commission)
| Input | Example |
|---|---|
| Professional time cost | 200 |
| Filing expenses cost | 150 |
| Admin support cost | 50 |
| Fixed overhead allocated to this matter | 100 |
| Target margin after commission | 25 % |
| Selling-price commission | 5 % |
| Calculated result | 714.2857 |
Delivery cost 400; allocated overhead 100; commission 35.7143; retained contribution after assigned costs 178.5714.
Choose reliable inputs
Account for delivery time, review work and when you expect to be paid for each engagement. For this legal practice calculation, use time sheets, engagement scopes and invoice ageing and a consistent definition of one matter.
- Professional time: include the portion belonging to this matter or reporting period, and record where the value came from.
- Filing expenses: include the portion belonging to this matter or reporting period, and record where the value came from.
- Admin support: include the portion belonging to this matter or reporting period, and record where the value came from.
Use the same currency for every money input. Do not mix weekly costs with monthly revenue, or count the same expense in both an itemised cost and allocated overhead.
How should commission change my quote?
Adding a commission percentage to cost does not preserve the target margin. Commission is based on the selling price.
Allocate overhead once; target margin and commission together must be below 100%.
What if this input changes?
If professional time cost rises by 10%, this example changes by 28.5714 . This shows the effect of one change; it does not predict what will happen.
Open the calculator, save your baseline, then change the input supported by the least reliable estimate in your records. Compare both scenarios before committing to a price or capacity promise.