Can I request retirement at my 20-year total time mark if I have 20 years of combined active and Reserve time? How does that impact Tricare?

You will need the points equivalent of 20 TAFMS years to retire with an active duty retirement where pay, tricare, and other benefits start immediately. Otherwise you will be a gray area retiree, and have to wait until 60 (60ish - depending on title 10 active duty for mobilization after a certain date, I think in 2008 if I remember right). Best bet is to check with your S1 folks if you’re ARNG or FSS if you’re Air Guard to see what all your point totals are and discuss your retirement plans/timing with them. I highly recommend trying to get a full 20 active duty years if possible, it will benefit you much more in the long run. I don’t think you can purchase tricare prime as a gray area retiree, but again I’d check with a career advisor or transition counselor to verify.