There is a Post Graduate Training Sponsored Program, that is designed to send selected officers to post graduate programs. This is competitive, and applicaple to specific occupations. For instance, a Logistics Officer may apply for an MBA program. Acceptance into this program incurs obligatory service - normally 2 months for every month of subsidized education.
A message comes out every year advertising this program in the Military. This year it was sent out in early August.
To get into the program the person needs to be occupationally qualified, normally with several years of occupational experience in the military, and accepted into the post graduate program (application is made to the university at the same time as application for subsidization is made). It is a competitive process, so there is no guarentee that the officer applying will be accepted.
There are also some technical programs for Warrant Officers. The Army has a specific program that provides equivalent to Masters education, and advertises about this time of year. That program is called Army Technical Warrant Officer Program (ATWO). I am not familiar with what the Navy or the Air Force offer, however, many of their Warrant Officers have advanced training as part of their occupational progression training.