Directive-type Memorandum (DTM) 16-005 - Military Service of Transgender Service Members, June 30, 2016 [open pdf - 412KB]
"This DTM [Directive-type Memorandum]  Establishes policy, assigns responsibilities, and prescribes procedures for the standards for retention, accession, separation, in-service transition, and medical coverage for transgender personnel serving int he Military Services.  Except as otherwise noted, this DTM will take effect immediately. It will be converted to a new DoDI [Department of Defense Instruction]. This DTM will expire effective June 30, 2017."
Directive-type Memorandum-16-005; DTM-16-005
Defense Technical Information Center: http://www.dtic.mil/