There's only one thing worse than a present you don't want — an unwanted gift you can't return.

Thanks to more restrictive policies adopted by many national retailers in recent years, it's tougher to return merchandise, especially when you've opened the packaging or don't have a receipt.

The Federal Bureau of Investigation believes organized retail theft costs merchants more than $30 billion annually, so it's hard to blame retailers for looking askance at those of us trying to take back ill-fitting sweaters, books we'll never read and electronics we already own.

It's a lot easier to blame the gift givers, or at least those who refuse to tuck a receipt under the wrappings. In a survey last month of 8,778 consumers, the National Retail Federation found that only about a quarter of them said they include receipts — either gift receipts or regular ones — with most of the presents they give. About 18 percent of respondents told the industry trade group they never include receipts with gifts.

The January issue of Consumer Reports warns that fewer merchants now offer store credit to those without a receipt. It's sometimes possible to locate an electronic receipt, provided the purchase was made by debit or credit card or by check. Consumers who pay cash often are out of luck.

Givers should include receipts. Recipients should not open the product packaging on gifts they know they don't want. That can be tough, especially if you get the gift in the giver's presence.

"If Aunt Tillie gives you the two-megapixel camera thinking it's the latest and greatest thing, and you don't want it, don't break the factory seal," said Edgar Dworsky, a consumer lawyer, former assistant attorney general in Massachusetts and the founder of the consumer-advice site ConsumerWorld.org. "After that, all bets are off."

Many merchants won't exchange or issue refunds for opened merchandise, provided it isn't defective. Some big retailers will accept the return, but they'll slap the consumer with a restocking fee of 15 percent or more of the product's cost.

Those fees are most common with electronics, but Consumer Reports warns that some stores — including Sears — also charge restocking fees on other items, too.

Computer software, video games, CDs and DVDs generally aren't returnable after the seal has been broken.

Even when goods are returnable, there's usually a return deadline. Big chains generally allow 90 days for returns on most items, but the time frames often are shorter for products that can quickly drop drastically in price, such as electronics, software and new-release CDs and DVDs.

That's why it's critical for shoppers to know a retailer's rules, which can change frequently and often aren't the same for in-store sales and online ones. The good news is many chains often have special, less restrictive rules during the holiday shopping season.

For example, Walmart usually requires that electronics be returned within 15 or 30 days of purchase. But the clock doesn't start ticking until Dec. 26 for purchases made between Nov. 15 and Dec. 25.