Where can gift cards for ITunes be used?
Your gift card can be used for purchases at any of the following online stores: the iTunes Store, App Store, iBooks Store, and Mac App Store.
Make sure that you are using the same Apple ID that you used when redeeming your gift card to make purchases from the above stores.
About your iTunes card
iTunes cards aren't interchangeable with Apple gift cards.
To check the balance of your iTunes gift you must redeem it to your iTunes account.
To redeem, visit appstore.com/redeem.
Once on your account, it cannot be transferred.
The balance of your iTunes card will be removed from your account for purchases until it is gone. From there you will need to pay by other methods or redeem another card.
About App Store & iTunes Gift Card
One card, millions of ways to enjoy it. Use the App Store & iTunes Gift Card to get apps, games, music, movies and TV shows. Available in a variety of denominations - spend it on in-app content, books, TV show subscriptions or even iCloud storage to secure files from all your Apple devices.