Apple has begun a new promotion in the US encouraging users to add funds to Apple ID accounts with their iPhone for app, music, movie, and game purchases. The new offer is giving up to $20 in bonus credit to users who use the iPhone funding method.
Apple started sending out emails with details on the new promotion offering the 10% bonus:
Now you can load money to your account more conveniently than ever right from the App Store. Then use your balance to enjoy games, apps, books, TV shows, Apple Music, iCloud storage, and more. Try it today and get an extra 10% added to your account.*
While this may sound confusing to US customers, in other countries, this funding/payment method is common for the App Store and iTunes Store and has been previously promoted by Apple.
Even if you normally use the credit card on file with your Apple ID for purchases, this option to fund via iPhone means you can use gift debit cards or other payment forms to purchase Apple ID credit for the App Store and more.
The new promotion caps out at $200 where users can get the full $20 bonus. The promotion is live until December 20th. Use the link here to take advantage of this limited time offer.
Alternatively, you can go to the App Store → Tap your profile picture in the top right corner → Add Funds to Apple ID.