Convert gold subscription into Game Pass Ultimate for the second time

To convert your gold subscription to Game Pass Ultimate, purchase a month of Ultimate, and it will convert your remaining Gold time to it.

If you add standard Gold/Game Pass while you have Game Pass Ultimate, the subscription is converted to Ultimate as well. The time is converted based on price rather than time so 12 months of Gold would have been converted to 4 months of Ultimate.

If You Get Game Pass Ultimate It Will Convert Your Xbox Live Gold 1 Year Into Game Pass Ultimate For The Remaining Time Left On Your Year Subscription. So For Example If You Have Xbox Live Gold Paid For A Year And You Upgrade To Game Pass Ultimate It Will Convert It To One Year Game Pass Ultimate Or However Many Months You Have Left Of Your Subscription.

(Make Sure It Says Upgrade To Game Pass Ultimate So It Will Convert Your Gold To Game Pass)

Your subscription is converted to Game Pass Ultimate and your Live Gold subscription time is converted. 1 year of Live Gold equals 4 months of Ultimate. Once you confirm, there is no way to undo it.

I agree with Wadski in that if you currently just have a Xbox Gold subscription, you are better off adding additional months to you Gold Subscription or Game Pass first before you convert to Ultimate. If it is your first time converting to Ultimate, the
total months of Xbox Gold plus the total months of Game Pass will be added as your new Ultimate subscription. 12 months of Gold + 3 months of Game Pass will convert to 15 months of Ultimate. If you purchase 3 months of additional Gold membership then you will
get 18 months of Ultimate. Therefore only purchase Ultimate after you convert your subscription.