If the mayor’s controversial proposal to overhaul admissions at specialized high schools were in place last year, more girls would have been accepted, and the number of charter schools with students receiving offers would have jumped by almost 50 percent, according to a review of the plan by the city’s Independent Budget Office.

The office also found that average grades for students with offers would inch upwards, but state test scores would slip notably in math (and slightly in English). Offers to Asian students would have been cut almost in half, but those students would still make up the greatest share of acceptances, according to the report released Thursday night.

In an effort to integrate the city’s coveted specialized high schools, Mayor Bill de Blasio has proposed eliminating the test that currently stands as the sole entrance criteria and instead offer admission to top-performing students. While black and Hispanic students make up almost 70 percent of the school system, their enrollment at specialized high schools is only about 10 percent.

It’s important to note that enrollment at the high schools might have looked much different than the IBO’s projections: The simulation is based only on offers to students, but some may ultimately choose to enroll elsewhere. For the year studied, the IBO reports that 16.5 percent of public school students rejected their offer to attend a specialized high school.

Many of the findings, based on data from the 2017-2018 school year, align with estimates already released by the education department.

“This independent report confirms our proposal will expand opportunity for top middle-school students,” education department spokesman Doug Cohen wrote in an email.

But officials took issue with some of the report’s findings, saying more recent test results show that a greater percentage of students would be considered proficient on the state’s English and math exams.

De Blasio’s proposal would require a change in state law, which currently dictates admission to the specialized high schools. His plan for shifting away from the single test would occur in two stages.

First, the city wants to expand the Discovery program, which offers admission to students who scored just below the cutoff on the Specialized High School Admissions Test. That proposal is being challenged in court by Asian parents who say it discriminates against their children. The specialized high schools are currently 62 percent Asian, even though those students only make up 16 percent of enrollment citywide.

The IBO report zeros-in on the second phase of de Blasio’s proposal: Eliminating the SHSAT and instead admitting the top seven percent of students from each public middle school in the city. Rankings would be determined by a combination of grades and state test scores, and students would also have to perform within the top 25 percent of their peers.

If the plan were in place last school year, the report finds that black students would represent 19 percent of offers, and Hispanic students would receive 27 percent of offers. That’s compared to 4 percent and 6 percent of those students, respectively, who actually got offers during the last admissions cycle. Offers to white students, meanwhile, would dip only slightly under the proposal— to 20 percent compared with the current 24 percent enrollment.

Read the full IBO report here.