The website states that the mailing address for Capital One payments is Card Services, P.O. Box 60501, City of Industry, CA 91716-0501. Card Services Inc., Attn: Exception Dept, 2012 Corporate Lane, Suite 108, Naperville, Illinois 60563 is the place to send overnight mail.
If you need to contact Capital One, the website suggests checking your most recent credit card statement for the correct postal address. If they choose to pay in full and on the same day, before 8 p.m. Eastern Time, they can choose the one-time payment option. AutoPay is another method of payment that can be set up once and then will automatically pay on the due date every month. The one-time payment and the AutoPay options are free of charge.
