With most credit card offers, every time you carry a balance from one billing cycle to the next you’ll be charged interest on the amount that wasn’t paid off yet.
When you’re charged an interest fee, it’s added to your balance.If you carry any of that balance into the next billing cycle you’ll be charged interest on it, including the interest the credit card company added to your bill last month!
This is called “compounding.” The bank charges interest on the entire balance you owe, including any finance charges you owe, every time interest is calculated. This is how credit card debt quickly snowballs into larger and larger amounts, and why it’s hard to make a dent in it.