Timing: Fiscal year 2020 Per Diem rates will go into effect October 1, 2019.
Background: Each Fiscal Year the Government determines the per diem rates for the Continental United States (CONUS). These rates are the maximum allowances Federal employees can incur for expenses while on official travel. The Defense Travel Management Office (DTMO) determines the rates for non-foreign locations outside the Continental United States, also known as non-foreign OCONUS (e.g. Alaska, Hawaii, Puerto Rico, the Northern Mariana Islands, Guam and other U.S. territories and possessions). The Department of State (DoS) sets rates for foreign locations.
Three allowances of the CONUS per diem rate:
Helpful DoD Per Diem links:
If you are required to have GSA per diem rates, access them here.