Image courtesy of Rockland Trust

A Boston developer will use $5.1 million in financing from Rockland Trust to convert a Financial District office building into 15 apartments.

Boston Pinnacle Properties acquired the 145-year-old office building at 281 Franklin St. on Feb. 23 for $3.8 million.

Known as the Henry Gustavus Dorr building, the brick and sandstone structure was completed in 1878 and previously sold for $6.15 million in 2017.

Under Boston’s downtown office to residential conversion program, developers receive a 75 percent reduction in the residential tax rate for up to 29 years.

The conversion would set aside three apartments for households earning a maximum of 60 percent area median income. Developers estimate the market-rate apartments would rent for $5.50 to $6 per square foot.

The 281 Franklin St. project  is expected to receive approval as soon as the Boston Planning & Development Agency board’s March 14 meeting.

“[Boston Pinnacle Properties’ Adam] Burns is a seasoned and innovative developer. By taking part of BPDA’s incentive, he is playing a vital role in addressing the need for housing opportunities in the city, and we look forward to seeing the project completed later this year,” Rockland Trust Senior Vice President Kenneth Ryvicker said in a statement.

Developers also have applied for office-to-housing conversions at 47-49 Winter St., 85 Devonshire St. and 258 and 262 Washington St. ahead of the June 2024 deadline.