Originally Posted by
sydneyracquelle
Some companies could interpret this as fraud. Same as if I buy an economy ticket, submit the receipt for reimbursement, cancel it, then use my miles for the work flight. You need to check corporate policy ahead of time.
Some employers also demand boarding passes for reimbursement. If you upfare the ticket, you'll get a new ticket number which will show on the boarding pass and not match the original coach ticket number on the original coach receipt that you apparently plan to submit. This will make clear that you did not get a free upgrade based on FF status.
I've sometimes had to explain the different ticket numbers when I use miles to upgrade the ticket. (My employer requires submission of all boarding passes for reimbbursement.)