The calculation
Fixed monthly salary equals basic monthly salary plus fixed monthly allowances. Basic salary does not change with employee or company performance, or because the employee takes medical or personal leave. Fixed allowances remain the same each month, such as a fixed food or housing allowance.
Payments excluded
Do not count variable allowances; overtime, bonuses, commissions or annual wage supplements; board fees, stock options or dividends; benefits in kind; reimbursements, including employment-related expenses; productivity incentives; employer pension/provident-fund contributions, including payments on the employee’s behalf; or gratuities on discharge, retrenchment or retirement.
Official source
Written independently from official MOM source material.