IN A MOVE to cut costs and rid the school district of tenured teachers not getting hired for standard classroom positions, Boston quietly paid out about $3.6 million between 2013 and 2018 in voluntary severance agreements to 63 teachers who agreed to resign from the city’s school system.

The settlements, negotiated between the Boston Public Schools and the Boston Teachers Union, came about as a result of reforms giving principals more autonomy in hiring teachers they want in their classrooms.

Prior to 2013, a small group of teachers typically ended up in an “excess pool,” either because their positions had been eliminated as a result enrollment reduction or due to state accountability rules that required teachers at chronically underperforming schools to reapply for their positions. Principals were required to fill openings from the pool, and teachers in the pool could exercise seniority rights to unilaterally claim positions.

Starting in 2013, the district moved to a system of “mutual consent” hiring that gave principals the final say over selecting teachers for their classrooms. Tenured teachers in the excess pool must now apply for open positions. Those not hired for regular classroom positions are nonetheless guaranteed by state law their full salary in positions of “suitable professional capacity,” such as assistant teachers, co-teachers, substitute teachers, or “academic interventionists.”

Under the buy-out offer, aimed at reducing salary expenditures, teachers who agree to leave the school department would receive severance equal to about 40 percent of their annual salary. Even with the severance agreements, there are currently 59 excess pool teachers working at BPS who are earning a total of about $6 million a year.

Although many of the settlement deals contain a nondisclosure provision, copies of all 63 agreements were obtained by filing a number of public records requests and appeals.

The Boston Teachers Union strongly opposed the release of the settlement agreements, according to sources, and at one point was even contemplating seeking a court injunction to prevent their release.

Matthew Dwyer, an attorney for the teachers union, said in a letter last December to Shawn Williams, the city’s director of public records, that the severance information should not be disclosed until he had an opportunity to fully investigate the legal rationale for disclosure.

The union eventually backed off from its position.

Sam Tyler, the former president of the Boston Municipal Research Bureau, a business-backed group that has supported efforts to give principals more autonomy in teacher hiring, said the settlement agreements make financial sense and shouldn’t be covered up.

“After all, it was public money that was used to pay for them,” he said. “I’m sure that both sides felt that they would be embarrassed if the settlement agreements got out.”

Tyler suggested the union leadership believed that they would be judged on how well they protected the interests of their members. “The reality is that these settlement agreements acknowledge that not all their members belong in the classroom,” he said. “A progressive union would have said, ‘We recognize that not all teachers are good teachers and these settlement agreements will help them move on.’”

The district’s new superintendent, Brenda Cassellius, and her predecessor, former interim superintendent Laura Perille, both declined requests for interviews to discuss the settlements.

Jessica Tang, the president of the Boston Teachers Union, also declined requests for an interview, but her office issued a prepared statement.

“As is common practice in many industries, Boston Public Schools and the Boston Teachers Union are required at times to reach settlements regarding separation terms for employees who are leaving the system,” said a spokesman for the union. “Departures from education jobs like any other job can range from reasons related to a disability, to career changes, or other factors unique to each circumstance.”

Most of the severance agreements bar the teachers from ever applying for or accepting future full- or-part-time employment with the Boston schools, except sometimes for substitute work.

Some of the agreements contained provisions requiring the employees to withdraw any pending grievances, the removal of letters from personnel files, and the Boston Public Schools agreeing not to contest the teachers applying for unemployment compensation.

All the separation agreements contained standard language that precluded the teachers from suing the district, the school committee, the City of Boston, and the union on matters related to their employment.

“This is a sensitive issue for both BPS and the union,” said Tyler.  “I think the school department would like to change the tenure law so that if a teacher is not selected by a school for two consecutive years, for example, they can be dismissed. But that would never make it through the Legislature.”