Hi lexandraloaiza,
Thanks for contacting Apple Support Communities!
We understand that you'd like to use a magnet card holder with your iPad Smart Case.
You can use a magnetic card holder with your iPad. You should be aware that magnets can interfere with medical devices and desensitize a magnetic strip on a card that is in the card holder. You can learn more here: Important safety information for iPad
"Medical device interference. iPad, iPad Smart Cover, Smart Folio, Smart Keyboard Folio, Magic Keyboard, Magic Keyboard Folio, and Apple Pencil contain magnets as well as components and/or radios that emit electromagnetic fields. These magnets and electromagnetic fields might interfere with medical devices.
Consult your physician and medical device manufacturer for information specific to your medical device and whether you need to maintain a safe distance of separation between your medical device and iPad, iPad Smart Cover, Smart Folio, Smart Keyboard Folio, Magic Keyboard for iPad or Apple Pencil. Manufacturers often provide recommendations on the safe use of their devices around wireless or magnetic products to prevent possible interference. If you suspect iPad, iPad Smart Cover, Smart Folio, Smart Keyboard Folio, Magic Keyboard for iPad or Apple Pencil are interfering with your medical device, stop using these products.
Medical devices such as implanted pacemakers and defibrillators may contain sensors that respond to magnets and radios when in close contact. To avoid any potential interactions with these devices, keep your iPad, iPad Smart Cover, Smart Folio, Smart Keyboard Folio, Magic Keyboard for iPad and Apple Pencil a safe distance away from your device (more than 6 inches/15cm, but consult with your physician and your device manufacturer for specific guidelines).
Magnetic interference. The Magic Keyboard and Magic Keyboard Folio contain magnets that hold iPad securely in place. Avoid placing cards that store information on a magnetic strip—such as credit cards or hotel key cards—on Magic Keyboard and Magic Keyboard Folio surfaces that attach to iPad, as such contact may demagnetize the card."
We hope this helps.
Cheers!
