Boston's planning and development agency on Thursday night approved a measure giving Amazon a tax break for proposed office space in the Seaport.

Amazon is negotiating a lease for forthcoming office space in the massive Seaport Square development.

The plan approved by the Boston Development and Planning Agency (BPDA) would give Amazon a $5 million reduction in property taxes in exchange for the company adding 2,000 workers.

Amazon would be entitled to a second $5 million tax break if it leased a second Seaport building, and brought in an additional 2,000 employees.

"We think [the measure] represents a unique opportunity for the city to work with that tenant on mutual goals about bringing jobs, tax revenue and expanding their presence," said Jonathan Greeley, the BPDA's director of development review.

Construction of the 18-story building is scheduled to begin this year, and be completed in 2021. The project is expected to generate 800 construction jobs.

The Seaport Square space is separate from Amazon's well-publicized search for a second headquarters — for which the Boston region is a finalist.

With reporting by WBUR's Newscast Unit. Click the audio atop this post for Bruce's Morning Edition conversation on the measure's approval.