Register to make your Citibank credit card payment online by visiting Citi.com, choosing the Credit Card option under the Sign On To option and clicking the Register Now link under the sign in box, as of 2016. On the registration page, enter your credit card number, name, security code and other personal information to create an account and link it to a payment source to pay your bill.
Online payments for Citibank credit cards take place on the Credit Cards page of Citi.com through a special account for which you must register by verifying your identity and linking it to the card in question. The registration process requires you to have the activated card present so that you can provide the security code that appears on the back. You also need to provide the last four digits of your Social Ssecurity number and answer other questions about the account before you can create your username and password.
After logging into your account, choose the Make a Payment option from the navigation bar to initiate the payment process. If you already have a checking or savings account with Citibank, it may appear as a default payment source on the account. If not, you need to link an external payment source, typically a debit card from another financial institution, and verify the funds before paying the balance.