Game pass ultimate and existing prepaid gold.

What happens to my prepaid months of Xbox Live Gold and/or Xbox Game Pass when I sign up for Xbox Game Pass Ultimate?

When you subscribe to Xbox Game Pass Ultimate, we’ll apply any prepaid time you have on Xbox Live Gold and/or Xbox Game Pass toward the Xbox Game Pass Ultimate plan, up to a maximum of 36 months. Prepaid time conversion rates are subject to change.

TXbox Ultimate Game Pass 1-month sub is $1 on XBL, includes Game Pass for PC, Xbox One, and Xbox Live Gold. Purchasing the $1 plan will upgrade your existing Xbox Live Gold/Game Pass memberships to Ultimate and combines both subscription months as Ultimate

I can't put my finger on the conversion rate data, at the moment, but it's approximately 3:1 Gold to Xbox Ultimate, if I recall correctly.

The benefit extended to the general public is the same that was offered during the Insider preview, in that existing Gold and Game Pass subscriptions were converted 1:1 when upgrading to Game Pass Ultimate. Redemptions of prepaid Gold and Game Pass standard
codes after the account already has ultimate is also the same, with a reduced ration shown in the FAQ.

How long do you think the function of the user's existing prepaid xbox live gold months will be available, which are converted into game pass ultimate months-when you switch? Thanks.

Did a bit more digging in the FAQs, no issues at all for existing Game Pass members (direct quote from FAQ):

If you're already an Xbox Live Gold or Xbox Game Pass member, any days remaining in your membership(s) will be converted to Xbox Game Pass Ultimate at a conversion ratio when you redeem the 24-month Xbox Game Pass Ultimate
membership and added to your Ultimate membership up to a maximum of 36 months. Xbox Game Pass Ultimate memberships are limited to 36 months.

If you’re already an Xbox Game Pass Ultimate member, wait until your existing membership has a prepaid balance that is less than 12 months before redeeming the 24-month Xbox Game Pass Ultimate membership through Xbox All
Access. You will be unable to redeem with more than 12 prepaid months of Xbox Game Pass Ultimate.

To check your prepaid balance, go to https://account.microsoft.com/services. Note, once converted to Xbox Game Pass Ultimate, Xbox Live
Gold and other Game Pass memberships cannot be unconverted. Learn more at www.xbox.com/gamepass.

If you add a prepaid Gold or Game Pass card while you have a Game Pass Ultimate subscription, the Gold/Game Pass is converted to Game Pass Ultimate at a conversion rate based on the price of the subscription, not the time 12 months of Gold is equal to
the price of 4 months of Game Pass Ultimate. In order to add a prepaid Gold (or Game Pass) and get the full time, you would need to either cancel your Ultimate subscription or wait for it to run out and then add the code after the Ultimate subscription has
ended.