Monday, November 26, 2012--5:55p.m.

MADISON--Purchasing online can be easy--you can even do it from home in your pajamas--but you need to pay attention to your receipt.

Here's why: you're supposed to pay sales taxes on the things you buy.
But, not all online retailers will charge you for those taxes.
In fact, unless a retailer has a physical presence in a state, they're not required to charge you Wisconsin's sales tax.
But you're still supposed to pay those taxes.

A spokeswoman for the Department of Revenue says the state is being short changed about $150 million each year, because of unpaid sales taxes.

So how will you know if you've paid the taxes or not?
"The retailer that you're buying something from online or through a catalog.....it will indicate on your receipt whether or not you've been charged a sales tax," said Laurel Patrick, the communication's director for the Department of Revenue.

If you find yourself in the situation where you haven't been charged, what do you do? Patrick says you are required to report those online purchases on your tax forms. She says they'll tell you how to compute what you owe.