NEW YORK — It happens all the time. You open your bank statement or credit card bill, and there's a new fee assessed to your account that you hadn't counted on. Banks and credit card companies make billions a year from such fees.

To beat the fees, you'll need a strategy.

From Kiplinger Magazine, here are four tactics to consider:

1. Don't get complacent. Part of the reason why so many customers end up paying fees is they don't contest them. If fees show up on your account statement and you don't agree, place a call to the bank representative. In most cases, if you are a good customer, banks will give you a break.

2. Call on weekends. Few managers work on the weekends, and it may improve your chances of getting the fee excused if the manager is not around.

3. Do your research before you place that call. Find out just how valuable a customer you are to the bank. Figure out your average monthly credit card balance. If you have more than one card, then figure out the balances on those. If it's a debit card account, write down your average monthly checking balance. Be prepared to say how many years you have been a customer. Use these numbers as ammunition on the bargaining table.

4. Be realistic about your time. If the charge is for $2, is it really worth it to spend 20 minutes on the phone to get it excused? Save your time and energy for those $25 charges.

5. Be polite. Don't lose your temper. Bank representatives are more likely to help you if you are nice to them.