In iTunes, your account balance shows how much money you've added to your account through gift cards or by using iTunes Pass at an Apple Store. When you buy anything from the iTunes Store -- music, movies, apps or books -- iTunes deducts the necessary funds from your balance, if you have one, rather than billing your credit card.
Location on Your Computer
In iTunes 12 on your computer, click Sign In and log in with your Apple ID, if you aren't already signed in. Click your name on the menu bar to see your account balance.
ITunes also shows your balance in two other locations: in the upper right corner of the window while in the iTunes Store and on the Account Information page.
Location on iPhone, iPod Touch or iPad
Both the iTunes Store app and the App Store app on iOS also show your account balance. In either app, open the first tab (Music in the iTunes Store app or Featured in the App Store app) and scroll all the way to the bottom of the page. You'll see your balance listed directly below your Apple ID. If you opt to have iTunes charge your credit card with each purchase, you won't see a balance.