Even if your not-for-profit rarely needs to reimburse staffers, board members or volunteers, reimbursement requests almost certainly will come up. A reimbursement policy will make the process easier and reduce the risk of any disagreements. Policies generally fall into one of two categories: accountable or nonaccountable. Reimbursements under an accountable plan generally aren’t taxable for recipients. But to secure this favorable tax treatment, accountable plans must satisfy certain requirements related to types of expenses, documentation and return of excess reimbursement. Be sure to address mileage expenses specifically.