If you take a business trip during which you also vacation, you can take allowable deductions for travel expenses (i.e. Your friend and you can split the cost of your trip expenses in several ways including: Equal split, Proportional split, personal Split.The Travel and Expense Module in OAKS FIN is used to process 2 types of expense reimbursements: Travel-related expenses. Non-travel related expenses. Business travel is tax deductible! Every dollar you spend on travel related to your business may help you legally save on taxes. (1) Ordinary and necessary expenses relate to your business travel may be reimbursed. Each expense must have a clear business purpose. Per diem is an allowance for lodging, meals, and incidental expenses. The US General Services Administration (GSA) establishes the per diem reimbursement rates.