Travel and subsistence expenses describe the cost of spending on business travel, meals, hotels, sundry items such as laundry (though usually only on long trips) and similar ad hoc expenditures.
[1] These reimbursements often have tax and related implications, and vary depending on the country of the business.
[2][3] An organization may refund or reimburse these costs on the basis of an itemized list, or may conclude that cost of doing so is disproportionately high and instead pay a per diem ("per day") allowance.
This provides a budget from which the traveler may recover their costs.
In this case, the traveler may choose to stay in more expensive hotels and pay the additional cost themselves.