The sweeping new tax law President Donald Trump signed this month will provide tax cuts to corporations and the wealthy.

But it will also deprive well-heeled sports fans of a perk that benefits major college athletic programs—a tax deduction for ticket-related contributions.

Here's how it has worked, according to Forbes magazine: Popular programs, such as the University of Oregon Ducks football team, have generated great demand for season tickets and luxury suites.

In college programs like the one in Eugene, where demand for season tickets and luxury boxes outstrips supply, programs have been able to require fans to make a "donation" to the athletic department in exchange for the opportunity to purchase season tickets.

So, obtaining desirable seats is tied directly to contributions. Here's how it works currently for Ducks season ticket holders:

"The goal of the University of Oregon's priority seating policy is to achieve an equitable distribution of priority seating in Autzen Stadium and Matthew Knight Arena," the U of O's season ticket policy says. "As always, the intent of our policy is to reward those who have been long-time supporters of Oregon Athletics, while allowing new donors the ability to acquire appropriate seating for their annual contributions in support of our athletic scholarships."

In 2016, according to U of O figures, contributions to the athletic department totaled $27.8 million, a little more than a quarter of the department's $110 million budget. (It is unclear what percentage of the donations are tied to tickets and what percentage are outright gifts with no strings attached.)

Under current law, fans can deduct 80 percent of the donation they make in order to get tickets.

So if a Ducks fan gives the athletic department a $10,000 donation for the right to purchase season tickets, the fan can deduct $8,000 from pre-tax income.

Critics of the ticket-related deduction say that fans often get the right to buy something—scarce tickets—that has a value greater than the actual donation, when the deduction is factored in.

Former President Barack Obama proposed eliminating the deductibility of donations connected to season tickets in 2015, but Congress panned the idea then.

But the GOP tax reform has scuttled the deduction. Now, if a Ducks fan gives $10,000 in a ticket-related donation, she can deduct nothing. (Donations to the athletic department unrelated to tickets are still deductible.)

Some big sports universities are scrambling to limit their losses. The University of Alabama's athletic director recently wrote to boosters, who gave $25 million in ticket-related donations last year, encouraging them to make next year's donations before the end of 2017, in order to tax one final deduction before the next tax law takes effect in 2018.

A spokesperson for the University of Oregon athletic department did not immediately respond to a request for comment.