Your statement cycle is 30 days, and after that period, you have 30 additional days to pay your statement balance. So technically, your statement is due 60 days after the first day of your statement start date and 30 days after the end of your statement period.
Sound confusing? Let's break it down
Let's say your statement date begins on the first of the month. You spend $100 during April, and now it's the middle of May and you've spent an additional $200 on your card. Even though your balance is currently $300, your statement balance is only $100, because it's the total you spent during your statement cycle in April.
You have an additional 30 days after your statement cycle ends to pay that $100, so you have $100 due by May 30th.
If you end up only paying a portion of that $100 (say $70) by the end of May, the remaining $30 will get tacked on to your May statement balance, which is due by the end of June (or 30 days after the statement end date). You will pay interest on that $30 because you didn't pay the entire statement balance by the statement due date.
If you do not pay your entire statement balance before the statement due date, you will incur interest. If you do not pay the minimum payment listed on your statement, you will incur a late fee.
View your cardholder agreement for more details. If you have the Rocket Money app, it's located within your Card account under "Manage" > "Card Profile & Settings".