Beginning Sunday (1/27), merchants will be allowed to pass along a 4% credit card use surcharge when you pay with plastic. But you have choices that can save you money.

Now, this will not be adopted immediately by every merchant, nor will it apply to every credit card. For example, reports American Express will likely be exempt from the new provision.

Nor will every resident of every state face such a surcharge. California, Colorado, Connecticut, Florida, Kansas, Maine, Massachusetts, New York, Oklahoma, and Texas all expressly prohibit the surcharge.

In the past, some merchants were using prior rules to offer customers a cash discount. I've already seen gas stations with dual pricing for cash and credit.

Let's say, for argument's sake, that gas is $3.50 a gallon. You may see that as the cash price and $3.64 a gallon for a credit card transaction. You will have to decide which price you want to pay. (Debit may be considered as cash, at the discretion of the gas station.)

A 4% credit card use surcharge when you pay with plastic.

If you're a merchant, how you position this new change to customers will be key.

My wife and I go to a restaurant that used to be cash only. Then they changed their minds and started accepting credit cards -- except for American Express because of its high merchant fees. They also increased their menu prices by 10% -- far more than merchant processing fees -- at the same time they started accepting credit cards.

So what happened? Their average ticket went up because too many people have a disconnect between real money and plastic. They're freer with spending on plastic than they would be if they were living a cash-only existence.

The moral of the story is if you see a cash discount, you can get a double benefit: You're likely to be more careful with your spending when you pay in cash, and you won't be paying the new credit card surcharge.

Either way it adds up to same thing. More money in your pocket!