A billing cycle begins on the date when the account is created. The billing date will typically be the same day of the month each month - for example, a cycle that starts on the 20th of the month will always be billed on the 20th. If the billing date falls on the 31st of the month, or a date that does not exist that month, it would default to the last day of the month. For example, a cycle starting on January 31 bills on February 28 (or February 29 in a leap year), then March 31, April 30, and so on.