Can you pay for a year in advance

iCloud storage will be billed to your AppleID monthly. There are no annual plans as they were discontinued years ago. As mentioned, you can preload your AppleID with a years worth of credit, but the fee will still only be deducted every month on the monthly schedule.

If you're referring to iCloud storage, only with iTunes Store gift cards.

If you're referring to non-Apple storage, check the options provided by the host or seller.

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