Can I serve fifteen years in the Reserves after my active duty contract expires, and still retire at twenty years with a pension?

Next question: can you serve 15 years on AD then be transferred to Reserve Retired status w/o a 20 year letter and stay gray area retired for life? The answer is yes.

I served 12 years active duty, followed by 12 years in the National Guard. I am enjoying my pension and benefits. It is a good deal for me.

Yes. Remember that NO retirement benefits begin until age 60. Further if you are rated as a disabled veteran by the VA, your monthly retirement will be reduced if you receive monthly benefits from the VA. Figuring out reserve retirement pay is convoluted at best. As has been said, points, points, points. Taken all together, is it worth retiring from the reserves, yes.

I joined in 1975 and got out reenlisted after 9/11 and served my twenty at 65 now there trying to take Tricare away from me or anyone else having this issue

I retired as a Staff Sergeant in the National Guard. When I retired I had 13 years active duty, 8 years Gurad time. My current retirement pay is $1,681.00. So yes you can retire with 5 years active service and 15 years reserve or National Guard time. The reason I did not leave the Guard at 20 years was because you have to serve at least 8 years minimum to get a pension. My total military time adds up to 21 years. I also have 2 years inactive time, but this does nothing for my pension.

yes,you can retire but you don't get your pension until 60 years old. Your retirement pay is based off of a point system.

I am very glad you asked this question. I was an E6 when I got out at 17 years reserve only. Do I qualify for retirement and medical at age 60? I did serve active duty/deployment in '98 in Bosnia for 8 months. That is the extent of my active duty.

You have gotten very good answers so there is that,
This is similar to what I did and am at 58 so I am getting close to getting the retired pay.
Good thing is if yougo the route you are proposing you will have alot more time with the family and the ability to use your GI bill right away and get in a nice career with hopefully, a good retirement and you can draw both and be comfortable.
At least your not wasting your 5 years I think that is a good choice.

What the MSG said. Also, here is a handy calculator on the Army HRC portal: https://www.hrc.army.mil/content/Army%20Reserve%20Retirement%20Calculator

As they say, it’s all about the points to make it worth it. Do little, get the min. Civ job ease with you coming going, and family, determine how much you can do. If you want, volunteer for long term temporary staff assignments and such, get more and see Germany, Korea, Japan, Hawaii, etc...(and lots a times you have family with you). I had 4yrs active and 26 reserve and ended up at 47% and began drawing at 55 1/2yrs old. It’s all what you make of it. Enjoy the ride while it lasts!