When Texas Rangers shortstop Alex Rodriguez stepped onto the field at the All-Star Game last July in Milwaukee, there was a huge cheer from the crowd.

There may have been cheering at the Wisconsin Department of Revenue as well: By appearing in the event, Rodriguez obligated himself to pay more than $8,000 in Wisconsin income taxes.

Rodriguez and hundreds of other athletes and entertainers are finding that some of their biggest fans are state tax collectors. A growing number of states -- and some cities as well -- are aggressively pursuing high-income non-residents who earn income from within the states' borders.

This ultimate commuter tax -- often dubbed the "jock tax" -- is creating a major headache for its targets and has spawned a cottage industry of accountants and bookkeepers who advise high-profile figures on how to minimize their state taxes, prepare returns and make payments for taxes they cannot escape.

Players sometimes move to a different state, which accountants say can help when it comes to items like signing bonuses, but they have little choice about where they play their games.

"It's a nightmare," said Ronald Rubin, a certified public accountant in Bethesda who does tax returns for several professional athletes. "You have some players filing 12 or 14 state income tax returns."

The players "moan about it, but it's really a pain for the accountants," said former Washington Capitals goalie Bernie Wolfe, who now runs Bernard R. Wolfe & Associates Inc., a financial planning firm in Chevy Chase. "They have this tax return that's about the size of an atlas -- a hundred pages for a tax return. They bill the player and the player gets upset because of the costs."

Stars like Rodriguez, who make millions of dollars a year, get little sympathy, and accountants and state officials say they generally pay what they owe.

"You see at the end of the year your paycheck comes in and you have 15 different states that take out money," said Washington Capitals left wing Steve Konowalchuk, who earns around $1.5 million a year. "It's kind of weird."

Agents and others, though, say many marginal players, who may have careers lasting only a few years and paychecks far smaller than A-Rod's, can see a significant portion of their earnings drained away by the jock tax. The tax also applies to coaches, trainers, equipment managers and others who travel with the team, though many of them make fairly modest salaries.

States have long asserted the right to tax income earned within their borders, but the soaring incomes of athletes have given the jock tax special significance. The fiscal woes facing many state and even municipal governments have made them more aggressive in their collection efforts.

"Maybe 10 years ago no one should have done this, but since others have done it, we felt we owed it to our citizens to be collecting this tax," said Cincinnati city councilman David Pepper, who in December helped pass a law applying a 2.1 percent earnings tax to out-of-state professional athletes, which is expected to bring in about $750,000 to the city. "If we don't do whatever anyone else does, we're the ones with the 'kick me' sign on us."

Some experts say the tax is unfair because it singles out certain groups.

"It's not fair [that] just because this particular occupation is so easy [to track] and no one feels bad for" the rich players that they have to pay these taxes, said David K. Hoffman, an economist with the Tax Foundation in Washington.

Hoffman argues that the players are paid by their teams in their home states and are not in fact earning their money at away games. In addition, he said, "the cities and states are the ones that benefit. When a famous athlete goes to a city that doesn't have the most popular team, he fills the seats. But his paycheck doesn't change."

Hoffman, who calculated the taxes incurred by Rodriguez for playing in the All-Star Game, figures that Wisconsin pulled in more than $133,000 from all the players in amounts ranging from A-Rod's $8,864 to $58 each from National Leaguers Eric Gagne and Jimmy Rollins.

States argue that their taxes are equally applicable to everybody, but some concede that practical considerations do play a role. Maryland, for example, doesn't try to tax airline pilots, though their situation might seem analogous to athletes', because "it's not considered enough of a significant activity that they are involved in when they stop briefly" in the state, said a spokesman in the comptroller's office. Also, it would be a "bureaucratic nightmare . . . trying to assess what percentage of their salary should be taxed. It's just not doable."

But where the tax can be collected easily and in large amounts, states are interested.

California, which is looking at a $35 billion budget deficit and has 15 teams among the four major professional leagues, has an employee assigned almost exclusively to keeping track of the comings and goings of professional athletes: Duane Hoffman, associate tax auditor with the California Franchise Tax Board and the man in charge of the non-resident athlete audit program.

Hoffman said the state is an equal-opportunity taxer.

"We don't just pick on athletes," he said. "The law is designed for everyone who is doing business in California."

Hoffman pores over sports publications and online sites analyzing which teams are coming from where, which players are playing, when they arrive and when they leave.

"I am the only one in the office who gets to legitimately look at the sports [Web] sites," he said.

"This is a guy who knows the injury and waiver wire better than many managers," said Stephen Kidder, a Boston tax lawyer who represents the players' unions in Major League Baseball, the NHL and the NFL. "[Hoffman] knows exactly who is here and who is on the plane and on the roster."

"There is one state I won't mess with," said Kimberly Morton, who handles the tax returns of professional athletes for CSMG Inc., a major sports agency. "If you get on the bus and step foot in the state, California will find out."

The tax also is of interest to residents of the Washington area. Although the District of Columbia is barred by Congress from taxing D.C.-source income of non-residents, Mayor Anthony Williams has talked of seeking permission to tax the payroll of a baseball team, were one to move here, to help pay for a new stadium.

Most states that tax visiting athletes, coaches and others traveling with the team base the levy on what is known as "duty days," which are defined as the number of days an athlete is actually earning his salary.

In Major League Baseball, the athlete is considered to be paid from the beginning of spring training to the end of the regular season -- roughly 220 days. If the player earns a salary of $1 million, that number is divided by the 220 duty days and the player is considered to earn $4,545 per duty day. If he visits San Francisco for a four-game stand, California will tax him on the income earned while he was in the state, which comes to $4,545 per day over four days, or $18,180. At the state's approximately 9 percent marginal rate, the athlete might pay $1,636 in California state income tax for the four-day stand in San Francisco. Basketball may have as many as 270 duty days, and professional football about 180, depending on whether a player's team reaches the playoffs.

From there, the jock tax gets complicated very quickly.

Experts at Tanton and Company of New York City, a nationally known firm that specializes in tax returns for professional athletes, said each state defines "duty days" differently. Some include the preseason schedule, while others include only regular season games.

Most states consider an NFL game to constitute two duty days because teams arrive on Saturday for Sunday games and leave Sunday. NBA and NHL games are usually two days because the teams arrive the night before a game and go on to the next city immediately after the game.

Some states, of course, don't have an income tax at all. Players who live and play for teams in these states, including Texas, Florida, and Washington state, aren't taxed when they are at home -- only when they play games in states that do have a tax.

The District is perhaps the strangest situation of all. Barred from taxing non-residents, it can't even tax the home-team players, let alone the visitors, unless a player lives in the city, which few do.

Thus, when the Redskins left Robert F. Kennedy Memorial Stadium in the District for FedEx Field in Maryland, they subjected visiting players to state income taxes (Maryland's) they had not had to pay before. This was especially painful for players from no-tax states.

It made no difference to the Redskins themselves, however, since Maryland and Virginia, where the Redskins are based, have, like many states that abut one another, a reciprocity agreement. This means that when a Virginia resident works in Maryland, Maryland collects Virginia taxes and remits them to Virginia -- and Virginia does likewise when a Maryland resident works in Virginia.

And there is the principle that a taxpayer shouldn't be taxed on the same income in two different states. As a result, states give credit to their players for taxes paid on away games.

For example, when a Washington Redskins player who lives in Virginia pays Arizona taxes because the Redskins played the Cardinals in Arizona, the state of Virginia recognizes that he earned the money in Arizona and doesn't charge him tax on those earnings.

"I don't think it's a big deal money-wise because there are [tax] offsets in Maryland," said Konowalchuk. "It's probably a bigger hassle for the accountants."

Super Bowls, playoff games and all-star games present another opportunity for state tax collectors.

David Hoffman of the Tax Foundation calculates that the combined earnings of the 60 players at last summer's baseball all-star game totaled $3.3 million, on which they paid a total of $133,000 in tax to Wisconsin for that single appearance.

"I just drool when the playoff games are here," said California's Duane Hoffman, adding that the jock tax brings in around $80 million in revenue to California from out-of-state residents. That's less than one-tenth of one percent of the state's $96 billion 2003-04 budget. And the net tax effect is far less, because while California is raking in taxes on out-of-state players visiting the Golden State, it is also handing over money to California players in the form of credits against taxes those players must pay in other states.

Though California and other states benefit from taxing players from states such as Texas and Florida, which have no income tax and thus don't hit visiting players, many are just breaking even and impose the tax only to keep from losing revenue to others that are doing it.

"It would be much simpler if states simply taxed their own teams and don't look to visiting athletes for revenue sources," said sports agent Leigh Steinberg. "The amount of revenue derived from this tax is de minimis compared to the overall tax base for any municipality or state. It isn't as if the marginal revenue was going to keep schools open or stop libraries from closing."

"It's just a shift of taxes between the states," said Jan Plewes, head of financial services at Octagon Marketing and Athlete Representation.

Duane Hoffman said the income tax for non-residents has always been on the books, but it wasn't worth enforcing until athletes' salaries took off in the late 1970s and early 1980s.

"It wasn't cost beneficial when the guys were making less than $100,000," he said. "It doesn't make sense to go after a guy for $150. Another reason California is into this is the multiplicity of teams."

In many cases, teams withhold money from players' wages and pay taxes to the municipality or state in which the game is played. Those payments by the team can be made monthly or quarterly.

Some states, such as California and New York, monitor the process closely. Many states require the athlete to file a state tax return, with the result that many professional athletes have tax returns that stretch for hundreds of pages and cost several thousand dollars in accounting fees.

One way athletes can reduce their tax bill is to get as much money as possible up front in a signing bonus, and to receive that bonus as a resident of a tax-free state. If contracts are worded carefully, signing bonuses are not considered wages and an athlete can then avoid paying any state income tax, including the jock tax, on that money, agents say. The savings can reach hundreds of thousands of dollars for big-time players.

Sports agent Ron Del Duca saved client Tom Barndt, an NFL defensive tackle at the time, nearly $200,000 by advising Barndt to establish residency in Nevada before he signed a contract that included a $3.3 million bonus to play for the Cincinnati Bengals in February 2000.

"I basically told him, 'If you like Vegas and want to save some money down the line, establish residency,' " said Del Duca, of Virginia Beach. "But you physically have to show the tax people it's a legitimate relocation. You can't do it the day before you sign the contract."

Even without the signing bonus, players who live and work in a tax-free state can save millions in annual taxes.

Case in point: because Rodriguez resides in no-income tax states (Florida and, now, Texas) and plays half of his games in no-tax Texas, he avoids paying a state income tax on at least half of his income. At $25 million a season, half of his salary comes to more than $12 million. If he avoids paying, say, a 3 percent state income tax on that amount, Rodriguez is saving $360,000 free and clear. That's $3.6 million over 10 years.

"Tax planning is an important part of financial strategy for any professional athlete," said Octagon sports agent Gregg Clifton, who represents such big-name baseball players as pitchers Tom Glavine, David Wells and Baltimore Orioles outfielder B.J. Surhoff. "While we don't encourage athletes to move just for tax reasons, there's a clear benefit to relocating to tax-free states."

"It's definitely a consideration for free agents because 1 or 2 percent [in taxes] on a big contract starts to add up," said Capitals center Jeff Halpern, 26, who lives in Maryland and earns about $1 million per season. "A guy who plays in California is not making as much money as he would [if he lived and played] in Florida because of the taxes."

New York Yankees pitcher Wells, a native Californian, relocated to Florida in the early 1980s to be close to spring training and have easier access to offseason workouts. With his 16-year career earnings estimated to be in excess of $40 million, Wells has probably saved several million in state income tax, not to mention the interest that those savings would have earned over the years.

Steinberg, who has a long history of representing Dallas Cowboys stars such as Troy Aikman and Daryl Johnston, remembers some Cowboys bemoaning the Redskins' move in 1997 from the District to FedEx Field.

"The players always wondered whether this was one more nefarious Redskins plot to unsettle them on the eve of a big game," he said.