Apple has begun offering users the chance to add 10 percent extra credit to their App Store and iTunes accounts this week, similar to past offers from the company. For this deal, you'll have to add money to your Apple ID account from a credit or debit card connected to your account. 

To add the funds on your iPhone, visit the App Store, tap your profile picture, and then tap "Add Funds to Apple ID." Here you can choose from $1.00 to $200.00 to add to your account in order to get the 10 percent bonus credit. This means that the most you can get out of the offer is $20 in free iTunes credit when adding $200 to your account. 

The promotion will last through Friday, May 10 and is available in the United States as well as other regions, including Japan. With the credit in your iTunes account, you can rent or purchase iTunes movies and TV shows, buy books in Apple Books, pay for your Apple Music or iCloud subscriptions, and much more.

Source: macrumors