Cards can be declined for any number of reasons!
You'll receive an email notifying you when this happens, with a link to update your payment method:
You can also update it directly by following the steps below:
1) From the recurring donation page of your account click the three dots next to the donation subscription that failed, then click Settings.
2) Scroll to the Update payment method section. Click Add new to add a payment method on file or choose a different payment method already on file from the dropdown.
3. If you clicked Add new, return to the recurring donations page and repeat step 1 and 2 to select your newly added payment method.
Once selected, your donation will be charged using the new payment method on its next scheduled date.