Mayor Michelle Wu is proposing tighter requirements and more fees for development in Boston to help spur affordable housing production.

On Thursday, Wu proposed changes to the city's Inclusionary Development Policy that would require new multifamily buildings of seven or more units to include 20% affordability, a jump from the existing rules that require buildings over 10 units to have 13% affordability.

The mayor also proposed changes to the city's Linkage Policy, lowering the threshold for projects that must pay linkage fees from 100K SF to 50K SF while doubling the fees that lab buildings would pay.

"This will allow us to expand the pool of developments and proposals that will be contributing in this way to affordability across the city," Wu said at a press conference Thursday.

Both sets of changes need approval from the Boston Planning & Development Agency and Zoning Commission, while the IDP changes also must pass a City Council vote. The BPDA plans to begin holding public meetings on the changes in January.

The changes to the IDP would have 17% of the square footage set aside for residents making an average of 60% of the area median income and no more than 70%. Another 3% would be set aside for voucher holders, those making less than 30% of the AMI.

Changes to linkage fees, the amount a developer contributes to a city-run affordable housing fund, would be raised from $15.39 to $30.78 for lab space and $23.09 for all other commercial developments. The threshold for when the linkage fees kick in would drop from 100K SF to 50K SF. The last time the fee was raised was under former Mayor Marty Walsh in February 2020.

Lab buildings that also include office space would be considered on a “pro-rata basis,” meaning they would pay the higher lab fee for the percentage of the building that use occupies.

These new policy changes don't affect projects that have already filed with the BPDA when the changes are adopted, but a handful of developers have already begun providing that type of affordability. Tishman Speyer and Harvard University committed to making 25% of housing at the university's new Allston campus affordable.

"What we tried to do here is say, 'You need to have more affordable housing,'" BPDA Director and Chief of Planning Arthur Jemison said. "You can do it in a way that reflects the current realities."

In the weeks leading up to this announcement, Wu has faced pressure from city council members to raise the IDP, arguing that the existing requirements don't match the need for more affordable and workforce housing.

“We are now four years overdue for an update, and every month that goes by, more luxury developments are being approved," City Council Member Kendra Lara said in a meeting earlier this month. "We’re losing the chance to get long-term affordable units we need to stabilize our neighborhoods.”

During the conference, Jemison previewed the rollout of a new system within the next six months that would help create a more predictable process for developers going through Article 80 review.

These changes are the latest in a string of efforts from the Wu administration to boost affordable housing production in the city.

Wu has discussed raising the IDP since she was elected in November 2021, and she launched a study in April to better assess the impact of the changes. In January, Wu signed a home rule petition that codified inclusionary development in Boston’s zoning code.

In October, Wu signed an executive order to fast-track affordable housing approvals in the city, cutting the projected time to build new projects in half.

"This is one slice of a wide portfolio of changes that we are going to move forward to emphasize that everything you can possibly do at the city level is on the table to support affordability," Wu said.