Originally Posted by MSPeconomist

My employer's policy is that any airline vouchers (same for hotels, car rentals, etc.) earned on business travel that's reimbursed by the employer are to be used for later business travel, regardless of the account that's funding the travel. This means that I never take VDBs for trips paid by my employer. We're pretty much on our honor to keep records and properly spend the vouchers for business travel as it would be extremely difficult to check this under normal circumstances.