Even if it is a fixed amount monthly, if you are taking proof of expenditure (up to the limit fixed for the month, and if the receipts of any employee are, let's say, Rs. 750/-, then he should be given 750 only and not 800. I hope you get the point). In such cases, it is not covered under ESI as part of wages because it is primarily reimbursement of expenses and not a fixed amount given irrespective of how it is used by the employee. If you are not collecting proof of expenditure, then it is covered as wages under ESI.