Svelte tax strategies are the focus of many an accounting office in large corporations these days. Saving millions (or hundreds of millions) of dollars in taxes makes a team of tax attorneys a very wise investment for most companies.

So, it comes as no surprise that the world's biggest retailer -- Wal-Mart Stores Inc.(NYSE:WMT) --- has one of the more clever tax strategies I've seen in a while for a company that has thousands of outlets and locations across the U.S. Wal-Mart pays billions of dollars a year in rent for its stores, which are peppered throughout almost every state in the U.S.

But in a rather deft tax strategy, the company has been paying most of that rent -- we're talking about billions here -- to itself, and then it deducts that amount from its state taxes in the 25 states that allow the deduction.

Bottom line? This strategy has saved Wal-Mart from paying several hundred million dollars in taxes. Second bottom line? Wal-Mart is far from alone here. It's too bad state tax laws aren't very efficient at catching and sealing loopholes like this.