Boston Public Schools faces a budget deficit of up to $50 million for the coming fiscal year, as expenses increase and federal and state aid to the School Department declines, Superintendent Tommy Chang said Tuesday.

Chang, in a letter to parents, pledged that no schools would close due to the shortfall. But he said $20 million will be cut from the central office budget and $10 million to $12 million more will be saved by trimming the per-student funding formula, affecting the budgets of individual schools.

“Closing schools must be a deliberate process based on equity of access and student needs,’’ the superintendent said in the two-page letter. Long-term decisions about school facilities should wait until the completion of an ongoing facilities master plan, he said.

“We do not want to move forward with any dramatic changes absent that input, which includes the deep engagement of our community in the coming year,’’ he said.

Chang said that “a sizable gap’’ remains despite changes to school enrollments and programs that will further impact school budgets.

As the School Department prepared its annual budget early last year, it faced a nearly identical deficit of an estimated $42 million to $51 million, leading then-interim superintendent John McDonough to propose five school closures and other cost-saving measures. Ultimately, two schools were closed.

Tuesday’s letter provoked concern among many parents, said Kenny Jervis, who represents the Clap Innovation School in Dorchester on the Citywide Parent Council.

Jervis said significant cuts were coming to the Clap School, which his son attends, and even to Boston Latin School, one of the city’s prestigious exam schools, where his daughter is a student.

“The cuts are widespread and detrimental to a sustainable school, in many cases,’’ Jervis said.

At the Clap School, he said, at least $150,000 will be cut.

“This does not provide us with the opportunity to provide the students and the staff with the supports they need to create a program that’s equitable,’’ he said.

Systemwide, the cuts for the fiscal year that begins July 1 could be a “breaking point’’ that would force many Boston families to consider leaving the city, Jervis suggested.

Although the city has increased the budget appropriation for schools by $13.5 million for this year, salary and benefit increases for the School Department are running to $21 million, on top of unforeseen expenses and “investments in core operations, past commitments, and strategic priorities,’’ Chang said.

“While the city has continued to invest in the education of our youth, rising expenses are outpacing current revenue sources,’’ he said.

“The projected funding increase will not cover the full cost of our programs and services,’’ Chang continued, “especially given our commitment to important investments such as, early childhood education, the hiring of high-quality, diverse teachers and extended learning time.’’

He said School Department officials met with Mayor Martin J. Walsh on Monday to discuss the financial shortfall and the pursuit of additional support through grants, state funds, and partnerships.

A public discussion of the deficit will begin at the Feb. 3 School Committee meeting, Chang said, and continue with a series of public hearings in February and March. The School Committee is set to approve a new budget by March 23.

Jeremy C. Fox can be reached at jeremy.fox@globe.com. Follow him on Twitter @jeremycfox.