First Republic Bank will expand its Century City footprint by leasing around 31,000 square feet that will be vacated by Chicago-based accounting firm BDO USA at 1888 Century Park East, sources said.

Once the expansion is completed, expected next year, the San Francisco-based lender will lease approximately 100,000 square feet at the 21-story, 505,000-square-foot office tower.

“The space they’ll take is contiguous to their (current) space,” said John Bendetti, vice president of leasing at Commonwealth Partners, which owns the building.

First Republic Bank will expand after BDO USA moves its local office to the 47th floor of 515 S. Flower St. in downtown Los Angeles. The accounting firm signed a 15-year lease for approximately 28,000 square feet of space at the north tower of City National Plaza, Bendetti said.

“That’s great news for downtown,” he said. “The space they’re vacating is being back filled by First Republic Bank. That’s a win.”

Bendetti represented the landlord, Commonwealth Partners, which also owns the 52-story, 1.4 million-square-foot 515 S. Flower St. Jonathan Larsen, a principal at Avison Young, represented BDO.

BDO USA and First Republic Bank did not immediately respond to requests for comment.

Real estate reporter Ciaran McEvoy can be reached at [email protected] or (323) 556-8337.