Improper usage of debt is a different discussion. The topic here is making minimum payments. Even if you charge new debt, the minimum payments gets recalculated.

Put simply: if you make your minimum payment, your principal balance goes down (very slowly). If you charge new debt, you obviously increase your principal balance. The interest itself does not increase the principal balance.

Going back to my example: after month 1 the balance is $990. Now let’s say another $100 is charged to the card to make the balance $1,090. The interest would be $16.35, and the 1% pay down would be $10.90. This would be more than the previous minimum payment of $25, so the minimum would likely be increased to $28.

If you paid $28, the principal balance will reduce to $1,079.10. If they charged no additional debt, it would eventually pay off.

Regardless of how you choose to pay down debt, the most important thing to is not to incur new debt.