How we do it
Simple inputs, traceable math, official references.
CONUS rates are requested from the GSA Per Diem API by ZIP, fiscal year, and month. OCONUS trips are manual because foreign nation rates depend on DoD tables, currency, locality, and orders-specific authorization.
Departure and return dates create total days, lodging nights, first/last travel days, and full TDY days.
Lodging is capped by the daily lodging rate. M&IE is split into travel days and full days.
Provided meals reduce full-day M&IE using the breakfast, lunch, and dinner amounts entered or loaded from GSA.
The report shows lodging, M&IE, deductions, taxes or fees, other expenses, over-cap lodging, and suggested advance.
This calculator is not a government entitlement system. OCONUS, actual expense authorization, government quarters, unit policy, split disbursement, local vouchers, and travel office decisions can change the final amount.