So, I made it. I'm one of the 10,000 finalists for The Da Vinci Code Quest online puzzle game. At least six other Fools as obsessed as I also made the final cut, and we're all due to compete in a five-puzzle showdown that begins Friday for a grand prize estimated to be worth $128,170.54.

Therein lies my problem. Much as I want to win the four first-class trips for four to Rome, London, Paris, and New York and the attendant Sony gadgets that comprise the swag for the big winner, I'm loath to deal with the tax consequences. They could be huge. Sony says so in the contest rules:

All federal, state, or other tax liabilities arising from. the Contest will be the sole responsibility of Finalists and the Grand Prize winner. Grand Prize winner will receive an IRS Form 1099 from the Sponsor for the total ARV (approximate retail value) of the Grand Prize and the Finalist Prize stated above that he/she won in the calendar year won. (Emphasis mine.)

In other words, unless you want to add $128,170.54 to your adjusted gross income when you file your 2006 tax return, don't bother trying for the big prize.

And it gets worse. Sony doesn't want winners to sell one or more of their items to offset a big tax bill. Smaller ticket items, such as a high-definition flat panel display and a VAIO notebook computer, could potentially be sold for cash, but probably not for anywhere near full retail. I doubt either would provide enough to cover the IRS' cut.

That's why I called the Feds looking for help this morning. Their advice was to download this publication (links to a pdf file) and read page 31. It says, in effect, that the winner can include his own estimate of fair value of the grand prize in filing his return. "Fair value" is equal to the price at which a seller and a buyer can agree to a transaction, which means comparable sales from eBay or Amazon may qualify. But if the winner's estimated fair value materially differs from what Sony sends the IRS in its 1099, it could trigger questions and a request for documentation. (Gulp.)

I'm still thrilled to be one of the final 10,000 in The Da Vinci Code Quest. The games have been fun, and the final challenge should be really engaging. But the price of being first demands more treasure than I had bargained for. Da Vinci Code author Dan Brown may have sold 65 million books, but I haven't. Yet.

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Fool contributor Tim Beyers thinks the Da Vinci Code is an addictive piece of fiction. And, yes, he will go see the movie if he gets a chance. Tim didn't own shares in any of the companies mentioned in this story at the time of publication. You can find out which stocks he owns by checking Tim's Fool profile . The Motley Fool has an ironclad disclosure policy .