Every time I explain the credit card float to people, I feel like the bearer of bad news. There they are, happily paying their bills (for the time being) when I roll up and point out the flaw in their plan, like some self-appointed Safety Patrol of Personal Finance.

It’s not a fun role for me to play (okay, I don’t actually hate it), but it is an important concept to understand, so I’m going to take some time here to explain it.

(Don’t worry, I’m only writing warnings; there are no actual citations being issued. Yet.)

What is the Credit Card Float?

When you make a credit card purchase, you're given a grace period to pay things off. It's usually around 25 days. As long as you pay the balance in full by that due date, you are not charged interest. Many people take advantage of this, and even feel good about doing so. They charge their expenses this month, then pay them off next month.…