Sign up for Chalkbeat New York’s free daily newsletter to get essential news about NYC’s public schools delivered to your inbox.

When Mayor Zohran Mamdani secured a two-year delay in fully complying with the state’s class size law, the teachers union won a concession: Educators could receive pay bumps of up to $8,500 if their classes exceeded the caps.

But more than two months after the union announced the bonuses — and with the first day of class less than a month away — it remains unclear which teachers will receive them.

Teachers may be eligible for extra pay if their classrooms are exempt from the law because their building doesn’t have enough space or if their school can’t hire enough educators to staff smaller classes. But not every teacher in an exempt classroom will get a bonus, according to the union. The Education Department declined to explain how bonuses will be awarded or how much money has been budgeted for the payments.

Union officials contend the payments create a powerful “accountability incentive.” The possibility of doling out big pay bumps could push the city to shrink class sizes rather than seek exemptions from the law, which generally require union approval. Last school year, the city relied on thousands of exemptions to comply with the law, which generally caps class sizes at 20 to 25 students depending on the grade level.

But experts and advocates said the bonuses could disproportionately flow to teachers at more affluent schools, where classrooms tend to be more crowded. They worry that could exacerbate turnover at high-poverty schools by adding a financial incentive to move to a lower-poverty one.

“I wish they were using strategic compensation to do the opposite: to try to retain teachers in our lowest performing, traditionally hardest-to-staff schools,” said Evan Stone, CEO of Educators for Excellence, a teacher advocacy group that has raised equity concerns about the class size law. “The priority is about pressure to meet class size.”

Dan Goldhaber, a teacher labor market expert at the University of Washington, said pay differentials can help with retention. The city could strategically deploy them to the most effective teachers who wind up teaching larger class sizes in a bid to keep them in the system, he noted.

But the ambiguity about which teachers will ultimately get pay bumps could dampen the effect on retention, he said. There is no guarantee that teachers who receive the bonus this coming school year will get it again the following year when the value rises to $9,500. It’s unclear if the pay bumps, which count toward educators’ pensions, will continue after that.

“The effect would be a lot larger if it’s really clear what are the parameters of the program going forward,” Goldhaber said. “That is, I think, an example of a real missed opportunity.”

We’re on a need-to-know basis.

Every weekday morning, Chalkbeat New York is bringing thousands of subscribers the news on public schools and education policy that they need to start their day. Sign up for our free newsletter to join them.

Education Department officials are expected to hash out which classrooms will be exempt from the law by November, which means teachers won’t know whether they will receive a bonus until the school year is underway. This coming school year, the law requires 70% of the city’s classrooms to comply with the class size caps or win an exemption, which are subject to approval from the Education Department and unions representing teachers and principals.

The city’s Independent Budget Office estimated that at least 2,463 general education teachers could be eligible for the bonuses based on last year’s exemptions. If all of those teachers receive the full $8,500, the pay bumps could cost roughly $21 million in the first year.

United Federation of Teachers President Michael Mulgrew recently told Chalkbeat that the union is still hashing out details about the pay bumps. He declined to address concerns about whether teachers at more affluent schools will disproportionately benefit.

“We’re working through it right now, so we will let you know as soon as we are there,” he said. Union officials have previously suggested that higher-need schools would be “addressed first.”

Some teachers have expressed mixed feelings about the pay bumps. Robert Effinger, the union chapter leader at the Bronx High School of Business, said he is already trying to manage teachers’ expectations about them.

Most of the teachers who are aware of the bonuses have assumed they will be eligible for them, he said. “I have to patiently explain to them that it’s not that simple.”

One of Effinger’s social studies classes last year had 34 students — the current limit under the teachers’ contract — which generates significantly more grading and administrative tasks. His classroom is so crammed that he doesn’t have space for students to do group work or other activities, he said.

Effinger said he would rather teach classes of no more than 25 students than win a pay bump.

“The money is not going to make up for all the amount of work,” he said.

Alex Zimmerman is a senior reporter for Chalkbeat New York, covering NYC public schools. Contact Alex at azimmerman@chalkbeat.org.