Originally Posted by scambo1

The tax services in question provide you with your maximum perdiem vs reimbursement difference. So, for perdiem purposes, you don't need to keep records for unreimbursed employee expenses, if you uses one of the tax services.

For everything else, keep records - job travel, union dues, job education, professional/safety gear etc.

Basically, your receipts plus what you get from flightline, prodiem, etc get added together to give you your unreimbursed employee expense line value.