In order to get access to 0.99% fees for buy instantly, you must either have bought at least $5000 of Bitcoin or be on a prepaid annual plan of $50 or more per week.
If you are on no recurring purchase plan or a pay-as-you-go plan and have bought less than $5000 of Bitcoin, then your buy instantly purchases will be billed at 1.49%. See here for our full fee structure.
In order to switch from a pay-as-you-go plan to a prepaid plan, please click "Edit Plan" from your dashboard as seen below:
After clicking "Edit Plan", click, "Continue" in yellow. Then click, "Use Checking/Saving Account" in yellow, once you have the proper account selected.
That will take you to a screen (see below) where you can adjust your prepaid fees to "Prepay Annually" to get your 0.99% fee. After you select 0.99%, click "Save Changes" in yellow at the bottom of the screen.