How does your $3 cup of coffee suddenly turn into almost $40? When people spend more money with their debit cards than they have in their accounts, banks charge overdraft fees. But a new law meant to crack down on banks now gives consumers the option of whether or not to face that fee.

Let’s say you have $100 in your account and you want to buy $101 worth of groceries. The bank used to let you buy them, but then charge a fee—anywhere from $25-$35—for each purchase. But the new law says you now have to tell your bank if you want overdraft protection. If you don’t, your card will be declined at the grocery store and while you won’t be able to make your purchase, you also won’t be slammed with a fee.

"The embarrassment of being turned down at the cash register, for many people, will be better than being charged the extra fee," explains Edie Sutton, a money management educator at Purdue University Extension. "The key is to know what's in your account."

Sutton says in a world of direct deposit, automatic payments and online banking it’s easy to lose track of exactly how much money you have. But even though we may be past the days of balancing a checkbook, keeping strict watch of your finances is very important.

"All this electronic payment, electronic billing--it's very convenient but it also encourages people to be too spontaneous," says Dan Osberger, a financial advisor. "I personally don't use debit cards but all my kids do. They don't know how to write a check and they get nailed every now and then. And it's expensive and I think the banks were taking advantage of people. I think the overdraft fees have been outrageous and the banks have been making too much money off of them so I think it's good that they've put in some legislation that lets people opt-in or opt-out of the system."

Experts say banks will most likely add fees and charges to other activities to make up the loss in revenue, but several bank officials in Michiana say that’s not the case.

"I don't believe that our loss of income from any fees that we're going to lose will change or increase the fees on any of our other products," says Andy Haeck, First Federal Savings Bank.

Keep in mind, the new overdraft rules cover ATM and debit card charges but don’t apply to checks.

Here are a few tips to make sure you don’t spend more money than you have:

-Keep extra money in your account at all times, knowing it’s off limits to spend. It’s only there as a cushion in case of an emergency.
-You can connect your checking account to your savings account, but then you risk spending your savings.
-You can sign up for email or text alerts from your bank to let you know how much money you have in your account.
-Many people are ditching the plastic and only using cash to avoid extra fees.