Returns: watch out this holiday season.(Money)

You may chuckle now over the ugly holiday sweater your Aunt Edna sends you each year, but you could be in for a rude surprise when you try to take it back to the store, even if you've been shopping there for years.

"Each year at holiday time retailers examine their return policies and make changes based on their experiences with their customers," says Joseph LaRocca, vice president of loss prevention at the National Retail Federation, a trade group.

Many stores are getting stricter, primarily by employing computerized authorization systems to track and limit returns. The goal is to curb fraudulent returns, although innocent consumers can easily get snagged by these systems.

You can also get tripped up by store return rules that vary from retailer to retailer as well as within the same store. The rules at a store may change depending on the time of year, the type of item, and the method of payment.

BIG BROTHER AT THE REGISTER

Many big retailers, including Home Depot, Barnes & Noble, and Wal-Mart, now use proprietary software systems to monitor return behavior. These retailers are usually quiet about how they use the data, but Wal-Mart announced last year that it began using its return-tracking system to alert cashiers to customers who bring back more than three items without receipts within 45 days. Those customers must get a manager to approve their returns.

More than a dozen other retailers, including Express, K-B Toys, Sports Authority, and Staples, use the Return Exchange, which maintains return-tracking databases for stores. The company's system automatically instructs cashiers to reject returns when customers bring back items too often or for too much money. The Return Exchange would not tell us exactly how many returns cause your name to get blacklisted, saying it varies by retailer. The retailers we interviewed wouldn't give us a number, either.