“The new tax law exacerbates my findings and makes it harder for high-tax teams to put together a high-quality roster,” Petutschnig said.

The 2017 tax law set a $10,000 limit for the amount of state and local taxes that taxpayers can deduct on their federal returns — a pittance for professional athletes who live in states with high property taxes.

It also eliminated the prized deduction for unreimbursed employee business expenses, which for football players means that union dues and fees for agents, public relations, business management or off-season trainers can't be written off.

Texan advantage

A player for the Miami Dolphins or Houston Texans, where no state income taxes are levied, “was always going to come out a whole lot better than somebody playing in New York,” said Jerome Glickman, a director at accounting firm Friedman LLP who works with professional athletes. “Now, it's worse.”

Still, Glickman said the first priority for many athletes is to go where they think they're going to win. While taxes may be a consideration, they're rarely a deciding factor.

And some players choose to set up official residences in low or no-tax states, so a team's high state rate may not be such a deterrent.

Professional athletes do have to consider so-called jock taxes, which are levies that are calculated based on how many days a player provides professional services, such as playing in a game or training, in any state that administers an income tax.

Players on the New York Giants and New York Jets faced the third-highest average tax rate from 1994 to 2016 in Petutschnig's study — 7.94 percent.

Players on California teams, including the Oakland Raiders, San Diego Chargers and San Francisco 49ers, were hit with the highest average rate of 11.28 percent.

Patriots are an exception

A California team won on average 2.75 fewer games compared to a team in a low or no-tax state over 23 years of regular seasons, the study showed. That translates to losing 17 percent of the 16-game regular season — enough to make a difference in reaching or missing the playoffs.

Overall, Petutschnig's research found that a team above the median of 5.44 percent for average state tax rates wins, on average, almost two fewer games than a team below that rate.

In 2016, the average state tax rate for football teams that made the playoffs was 4.62 percent; for those that didn't, it was 5.93 percent.

Playoff exceptions

His study, which was presented at a recent annual meeting of the American Accounting Association, shows there wasn't a significant correlation between performance and tax rates before the NFL's salary cap in 1994.

Petutschnig focused on the regular season because, he said, playoffs and the Super Bowl are more susceptible to upsets and randomness.

Also, salaries for playoff games are paid by the NFL and don't count against a team's current $177 million salary cap.

In order to zero in on the effect of state taxes, Petutschnig controlled for factors that could influence a team's record in a season, such as the length of its head coach's tenure, the club's success in previous seasons, and the level of experience for its starting quarterback.

There are exceptions — most notably, the New England Patriots, who recorded the most regular season and Super Bowl wins from 1994 to 2016. Massachusetts' average state tax rate was 5.48 percent during that time period, slightly above the median.

Petutschnig credits the relatively low amount that Patriots' quarterback Tom Brady's annual salary takes out of of his team's salary cap, which means the team can afford to recruit better talent. Brady, now 41, became the Patriots' starting quarterback in 2001.

SALT factor

Now, a free agent considering a California team compared to a team in Texas or Florida would need to make 10 percent to 12 percent more to compensate for his state tax bill, said NFL agent Joe Linta, who placed quarterback Joe Flacco at the Baltimore Ravens and Kyle Juszczyk at the San Francisco 49ers.

The SALT limit is “a factor” in negotiations, Linta said.

Many teams don't max out the their cap, so they may have some wiggle room when recruiting players.

Joseph Criscuolo, a managing associate at accounting firm Drucker & Scaccetti who works with professional athletes, said that under the tax law, athletes “in the mid-range are going to break even,” with the law's individual federal income rate cut compensating for lost deductions.

But for the highest-paid athletes, the canning of deductions for unreimbursed expenses “is a big deal,” he said.

Under the old law, athletes could deduct those expenses if they exceeded 2 percent of their adjusted gross income.

Garoppolo's tax hit

“For well-heeled athletes making the big dollars, this hurts,” said Joseph Doren, the partner-in-charge of the sports and entertainment group at accounting firm PKF O'Connor Davies.

Doren said he sees a link between tax rates and team performance, adding that the Raiders — who will eventually move to Las Vegas in no-tax Nevada — have often made the case that unequal tax rates create an uneven playing field.

Quarterback Jimmy Garoppolo's five-year $137.5 million contract with the San Francisco 49ers will mean an additional $3 million tax bill under the new tax law, according to Alan Pogroszewski, president of AFP Consulting, an accounting firm for professional athletes.

Garoppolo would have saved $2 million in taxes under the new code had he instead signed with the Denver Broncos in lower-tax Colorado.

So far, the 49ers are off to a weak start; Garoppolo suffered a season-ending injury last month and the team has won just one game and lost five.

Most athletes “insulate themselves” from knowing much about taxes, said Criscuolo. “In theory, if they were a corporate executive, they'd be freaking out.”

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