Expense Module Setup, Expense Period tab

Expense Module Setup is under System Manager ⇒ HRPro Setup

Expense Period is the period to cover when calculating Expense Reimbursement for that payroll period 

When the offset is defined,  the Expense Period is the X days of the normal calendar period. E.g. offset is -10, The end date of the Expense Period is 10 days before the normal calendar month end. 

The expense Period can change only when there are no Expense transactions that exist. 

You can also define Expense Period in Global Working Hours and Roster Table.