Per diem, decoded
Every TDY authorization carries a lodging cap and an M&IE rate for the duty location. Eligible lodging is reimbursed up to your applicable authorized allowance. Costs above it require the appropriate approval or may be your responsibility. That's the entire business case for a crashpad: a fully furnished house priced at or below the locality rate, with DTS-ready receipts. Read the long version in our plain-English per diem guide.
Compare on base vs off base
Lodging on base is usually cheaper than the cap but not always available. Total both options for your dates — this tool for off base, the on-base lodging calculator for Air Force Inns — and decide before you travel.