Time & Expense with ESS supports two types of per diem methods: per diem as a ceiling and per diem as an allowance.

When per diem amounts function as ceilings, the system compares actual incurred amounts to the per diem rates listed in a schedule to determine if they exceed the ceiling, but reimbursement is for the incurred amounts. When per diem amounts function as allowances, the system reimburses the traveller for the per diem amounts regardless of the actual incurred amounts.