As San Francisco Giants slugger Barry Bonds closes in on Hank Aaron's career home-run record, a thorny question looms: If you're the lucky fan who catches the record-breaking home-run ball, what are the tax consequences?

The short answer: Find a very smart accountant, and if you don't like the answer, try someone else.

"Everyone's sure they know the right answer, but there's very little agreement" on what it is, said Phillip Mann, a tax lawyer at Miller & Chevalier in Washington and a former head of the American Bar Association tax section.

Bonds, who turned 43 Tuesday, hit his 752nd and 753rd homers on July 26, leaving him only three away from eclipsing Aaron's record of 755.

Common sense might suggest the answer is simple: The lucky fan who catches the historic ball shouldn't owe tax until he or she sells it. But relying on common sense to interpret tax laws can often lead to trouble.

Some professors, such as Alice Abreu of Temple Law School, feel strongly the answer is clear. "It's taxable income" to the fan the instant that person catches the ball, Abreu replied. How come? "It's accession to wealth," and nothing in the Tax Code specifically exempts from taxation a Barry Bonds-propelled baseball. Lawyers say this view logically stems from cases saying that someone who finds a "treasure trove" owes tax right away.

Other lawyers disagree. They also say it's highly unlikely that the IRS would be willing to risk the wrath of a baseball-loving nation by taxing the fan right away.

Yale Law School Professor Michael Graetz, a former Treasury Department official and co-author of a leading course book on taxation, says the issue "would make a great law-school exam question."

Actually, there's way more than one question. Will the Internal Revenue Service require the fan to pay tax immediately, based upon the ball's estimated fair-market value, or only after the fan sells the ball? Will the fan have to pay tax based on regular federal income-tax rates, which range up to 35 percent? Or, if the fan waits to sell the ball for more than a year after catching it, would any profit qualify as a long-term capital gain taxed at the maximum rate of 28 percent on collectibles?

If the prize catch does qualify as a long-term capital gain, what would the fan's cost be for tax purposes? Zero? The price of the ticket? The ticket price plus the value of a new baseball? What if the fan purchased a season ticket? Could he or she consider the cost of the entire season package as the cost basis? Would it make any difference if the person who catches the ball is a player standing in the bullpen?

These are just some of the curve balls that IRS officials don't want to try hitting. The IRS's expert is Don Korb, who not only is chief counsel but also the agency's resident baseball fanatic. His office is filled with sports memorabilia, especially those related to his beloved Cleveland Indians, including two home-run balls he personally caught. Last summer, he gave a speech at the Hall of Fame, where he discussed "the 10 most significant tax events in the history of baseball." If anyone knows the answer, it should be Korb.

When asked, Korb hid his head in his hands and replied, "Please, whatever you do, don't ask me that question."

A senior IRS official said that, to the best of his recollection, the issues involving milestone home-run balls haven't been addressed in any formal IRS guidance. Yet the IRS did offer its thinking on one aspect of the subject in 1998, and that helps explain why IRS umpires were reluctant to discuss the subject this week.

In the summer of 1998, a tax tempest flared up when St. Louis Cardinals slugger Mark McGwire was on the verge of smashing Roger Maris' single-season record of 61 homers. At the time, a reporter asked an IRS spokesman what might happen if the fan who caught the record-breaking ball gave it back to McGwire as a gift.

The IRS spokesman replied that the fan could get hit with a hefty gift tax. That response produced howls of protest from the halls of Congress, as then-IRS commissioner Charles Rossotti recalled.

The IRS quickly reversed itself. Rossotti issued a statement saying that if a fan caught the ball and gave it back to McGwire, the fan wouldn't be taxed.