258 and 262 Washington St. (right) seen in 2022. Photo by James Sanna | Banker & Tradesman Staff / File

Three downtown Boston office buildings would be converted into 95 apartments in the latest proposal responding to the city’s offer of tax breaks for residential conversions.

KS Partners estimates the cost of the project at 85 Devonshire St. and 258 and 262 Washington St. at $36 million.

The properties contain three connected 11-story buildings completed in 1899, including nearly 16,000 square feet of retail space that would remain.

Plans by Boston-based Embarc architects call for apartments with an average size of 640 square feet, including 54 1-bedroom units, 29 studios and 12 2-bedroom units. The project would include 17 percent income-restricted units.

A small project review application submitted to the Boston Planning & Development Agency did not list the current office occupancy rate of the buildings, but the class B office market in Boston’s central business district had a 25.5 percent vacancy rate at the end of 2023, according to a CBRE report.

Other developers also have presented plans for apartment conversions on Winter Street and Franklin Street. The office to residential conversion program encompasses Downtown Crossing, the Financial District, Fort Point, Chinatown and the Leather District.

The program offers a 75 percent reduction in the normal residential tax rate, currently $10.74 per $1,000 of assessed value, for up to 29 years. The application period ends in June.

The BPDA is expected to begin approving the first projects as soon as its March board of directors meeting.