The average credit-card late fee, now more than $27, has doubled in the past 10 years. Credit-card companies have also shrunk the time between when a bill is sent out and when it is due. Result: Many of us are shelling out more than we should.

With most credit cards, you lose the grace period (typically 22 days) if you carry a balance. This means that if you didn't pay off the entire balance last month, you're paying interest on what remains, plus you immediately start paying interest on any new purchases. If you do carry a balance and can pay only the minimum, do it as soon as you get your bill.

If you see a late fee on your credit-card statement — whether your payment was late or not — call to make sure the payment is in and ask if the company will remove the charge. If you're a good customer, it will most likely erase the fee.

If you know you can't pay a bill on time or at all one month, call the company and try to make a payment plan, says Olivia Mellan.