Housing Mitigation Requirements in Cumberland County: Portland's Inclusionary Zoning

A real mandate with real numbers, not a generic affordability goal

Portland first adopted an inclusionary zoning ordinance in 2015, requiring 10% of units in new multi-family developments to be set aside as affordable to households earning up to 100% of area median income (AMI). That requirement was substantially tightened in November 2020, when Portland voters approved a citizen-initiated ballot measure -- widely referred to locally as the "Green New Deal" initiative -- that raised the set-aside to 25% of units in any residential development of 10 units or more, and shifted the affordability target to households earning up to 80% of AMI (a stricter, lower-income standard than the original 100%-of-AMI threshold).

A developer who doesn't want to build the affordable units directly has a second option: a fee-in-lieu, paid to the city instead of setting aside actual units. That fee started at a $150,000-per-unit base in 2020, adjusted annually, and by 2025 reporting had risen to roughly $182,830 per required unit. For a developer evaluating a project of 10 or more residential units anywhere in Portland, this isn't background policy color -- it's a direct, quantifiable cost or design constraint that has to be built into a project's pro forma from the earliest planning stage, not treated as a later negotiation.

A documented effect on how much housing actually gets built

This ordinance's effect on development activity is itself a matter of public record, not speculation. Commercial real estate brokerage The Boulos Company's own analysis found that in 2020, before the tightened 25%/fee-in-lieu provision took effect, 756 residential units were put on the city's planning books; in the roughly one year after the new rule passed in November 2020, only 139 units were -- a decline of about 81.6%. Mainebiz separately reported the same broad trend under the headline "Residential construction permits in Portland down 82% since Green New Deal." Industry commentary (Boulos, Maine Policy Institute) has argued the flat per-unit fee structure particularly favors luxury developments, since a $182,830 fee is proportionally cheaper for a high-end unit than a modest one, while renters and future unit prices may absorb some of the cost rather than developer margins alone.

This page presents that production-decline figure as a documented, sourced fact about the ordinance's measured effect -- not as an argument for or against the policy itself, which remains a genuinely contested local political question. What matters for a land buyer or developer is that the effect is real and quantified: a project subject to this ordinance faces a materially different economics and planning-approval landscape than an equivalent project would have faced in Portland before November 2020, or than an equivalent project faces today in most of Cumberland County's other towns, none of which have adopted a comparable inclusionary requirement.

The ordinance is currently under a formal city review -- expect it to keep changing

As of December 2025, the City of Portland launched its own formal study to review the inclusionary zoning ordinance, following sustained developer complaints that the rules are stalling new housing projects even as the city faces a genuine housing shortage. This means the specific set-aside percentage, AMI threshold, and fee-in-lieu amount described on this page -- accurate as of the access date -- are actively under city reconsideration and could change as a direct result of that review. Don't treat the 25%/$182,830 figures as fixed; confirm the current version of the ordinance directly with Portland's Housing and Community Development office (Portland Housing Bureau, PHB) before finalizing any project's numbers.

What to check before planning a residential development in Portland

1. Confirm current inclusionary zoning thresholds (unit-count trigger, set-aside percentage, and AMI target) directly with Portland's Housing and Community Development office, given the ordinance's active 2025 review.
2. Get the current fee-in-lieu-per-unit figure directly from the city if considering that route instead of building affordable units on-site -- it's adjusted annually and has already risen substantially since the 2020 base amount.
3. Model both compliance paths (building the affordable units versus paying the fee-in-lieu) against your specific project's unit mix and price point before committing, since the flat-fee structure affects luxury and workforce-priced projects differently.
4. Remember this requirement is specific to the City of Portland -- it does not apply to development elsewhere in Cumberland County's other towns unless and until one of them adopts its own comparable ordinance, which this pass found no evidence of (Waterville, for comparison in a different Maine county, also has no such ordinance as of this pass).
5. Track the outcome of Portland's own 2025 inclusionary zoning review before finalizing a multi-year development timeline that depends on today's specific numbers holding steady.