In my experiences, they pay you what you are do no matter what. If you submit less on the invoice than you should get (and have receipts uploaded to show) the adjust up. If you submit more on the invoice than you should get, the adjust down. IF you are missing a receipt from, say, the inside part of the shop but not the gas part, they'll pay you everything except the inside reimbursement amount. (Speaking from experience now twice, darn it, losing that inside receipt)