Commission and overtime can be genuine, recurring income while still changing from month to month. A simple three-month average may conceal the difference between a stable base salary and a temporary peak.
Label the components
Start with contractual base pay. Then list commission, overtime, allowances and reimbursements separately. Reimbursements repay costs and should not be counted as earnings available for rent.
Choose a representative period
Three months may be adequate for routine overtime, but seasonal commission may need six or twelve months. The applicant’s role and available history should determine the period, and the final note should say which months were used.
Avoid forecasting certainty
Past variable earnings help describe a pattern; they do not promise future amounts. A review should give the decision-maker a transparent range and explain unusual peaks or gaps.