Just realized you have less than a day to make your Citibank Credit Card payment? No worries! You can still make payment on time through Citibank Online, Citi. Take advantage of the variety of offers available from Citibank, including banking products like checking, mortgage loans and credit cards. Pay your Citibank Credit Card outstanding in 3 simple steps. Provide your Credit Card Details. Enter your 16 digit Citibank Credit Card number or 14 digit.