Your can add different payment methods to your Apple ID for making purchases on the app store. The supported payment methods are credit cards, paypal, or gift cards. Gift cards add credit to your account which you then use up later however, if you want to add funds to your Apple ID without using a gift card, you can.
Add funds to Apple ID – iPhone
On your iPhone, open the Settings app and tap your name at the very top. On the next screen tap iTunes and App Store.
Once you’re signed in, tap Add funds to Apple ID. Select a denomination to add the funds, and choose your payment method.
Add funds to Apple ID – iTunes
You can also add funds to your Apple ID from iTunes. You can do this from any system that has iTunes installed on it and you’re not restricted to using the one system that you sync your iPhone or iPad to.
Open iTunes and go to Account. Sign in with the Apple ID that you want to add funds to. Once you’re signed in to iTunes, go to View my account. On the account summary screen, scroll down to the Apple ID Account section and click the Add funds to Apple ID option.
Again you will need to select the denomination for adding funds, and pick a payment method. The funds ought to transfer immediately. If you run into problems with transferring funds, make sure you have a valid payment method set up. If the payment doesn’t process, try removing the payment tool and adding it again.
If you reside in a country where online payment isn’t supported in the App Store, you won’t be able to add funds to your Apple ID. These stores are of course rare so in most cases you won’t have any trouble. You can also add funds to your Apple ID from the Mac app store.
At present, users who reside in the US will receive a little extra credit when they add funds to their Apple ID. To be precise, they will get 10% extra credit for any funds they transfer upto $200 which isn’t bad. This offer will expire on December 20th, 2018, so you want to hurry. If you make a lot of purchases on the App Store, this is a reasonably good deal from Apple.