Can’t use Apple Funds for iCloud+

Hi there DavidKnightley,

We understand you have a question about billing your iCloud+ storage to your Apple ID balance.

This resource may help: How apps, content, and subscriptions from Apple are billed

Specifically, check out the section below:

"Which payment method is charged?

When you buy items or pay for subscriptions, Apple attempts to charge your payment methods in this order:

1. Apple attempts to use your Apple ID balance to cover the full amount.
2. If you don't have Apple ID balance or you don't have enough to cover the full amount, Apple attempts to charge your primary payment method. The primary payment method is at the top of the list in Settings on your iPhone. You can control which payment method is at the top of the list.
3. If there's a problem with the primary payment method, or if the primary payment method can't be charged for the full remaining amount, Apple attempts to charge your other payment methods in order from top to bottom. If none of them can be charged, Apple might try again.

Some purchases aren’t charged to your Apple ID balance

• If you're in a Family Sharing group, purchases that you make are charged to your personal Apple ID balance. If you don't have enough Apple ID balance to pay for the purchase, the remainder is charged to the family organizer.
• You can’t use your Apple ID balance to buy gifts or gift cards.
• Some subscriptions might not be charged to your Apple ID balance.

If none of your payment methods can be charged

If none your payment methods can be charged, your account shows a negative balance. You can't buy more items or update your apps until you update your payment method."

Cheers!