Buying Ultimate 1 Month. Price to buy

So, how much money do I need to have on my account to get Ultimate 1 Month? It says $1.00 plus applicable taxes every month after that. But then, it says $14.99 every month after that. Do I need to have at least $16.00 on my account? Because I have $1.85
currently but it will not let me buy the Ultimate 1 Month. It mentions about "How do you want to pay the rest?"

The 1$ option is only available if paying by card but you can just buy the month with money on your account for usually 7.99 subject to cange. the make no money of the 1 $ optoin but they do on the further payments by card if not cancelled before the months
end

In order to use the funds on your account, you have to prove you can pay for the next payment. So you'd need either enough funds in your account for the next payment or a credit card/Paypal on file as well. How much you'll need exactly would depend on
how much tax is in your area.

If you're buying Ultimate while you already have Gold (and/or regular Game Pass) it will convert the remaining time you have into Ultimate at a rate of 1:1. So if you have 12 months of Gold and buy 1 month of Ultimate, you end up with 13 months of Ultimate.

If you go the opposite direction and have Ultimate and then add 12 months of standard Gold or Game Pass, the Gold is converted based on price rather than time. 12 months of Gold is equal to 4 months of Ultimate.

The price doesn't change, but what it'll do is convert what you've already paid for into Ultimate as well. So if you buy 1 month of Ultimate and add it to your Gold, you'll have about 13 months of Ultimate.

If you have Ultimate and add 24 months of Gold, then yes, it would convert to 8 months of Ultimate. The conversion is based on price rather than time. 4 months of Gold is equal to the price of 12 months of Ultimate. So if you were to convert that way, there
is no other 16 months of Gold. It's all converted to Ultimate.

If you were to let your Ultimate run out and then add the Gold so you have a standard Gold subscription and then add Ultimate, it will convert at a ratio of 1:1. So for example, if you let your Ultimate run out, then add 24 months of Gold, then buy 1 month
of Ultimate, you end up with 25 months of Ultimate.