Tenchi Ryu
Ashtray B!tch
First in order for this to work, you have to be a Insider Delta member which requires 20 points in the program which is easy as hell to get and being a member of the insider hub thing for at least a month (looking at my friend list several of you have). So even if you are not one sign up now cause they did this promo last month so they will likely do it again.
Did all that? Next part
1. Go into Microsoft Store on Xbox One
2. Search Xbox Game Pass Ultimate
3. Opt in, they will charge you $1 and will consolidate your remaining Game Pass and Live Gold months into the same # of months of Game Pass Ultimate. Up to 36 months. This is open to insiders and was also listed in the fine print of the sale starting today, so it may be open to the public. If not, join the Insiders program ASAP and do a few quick surveys to reach level 2, join the Xbox One Update beta program, and you should be able to test GP Ultimate. IIRC, when Ultimate officially launches, it will come with Game Pass PC.
I had stacked Gold all the way until Oct 2020 and was paying 10 a month for game pass. My Gold and remaining gamepass month was merged and converted into the program and now I have Game pass ultimate until December 2020 after which I'll get charged 15 bucks a month.