A Portland multi-unit listing comes with a rent roll, and most buyers read it the way they would anywhere else. They look at the current rents, compare them to market rents, and assume the gap is upside they can capture after closing. In Portland that gap is often fixed by law. The City's base rent for most covered units is the rent charged in June 2020, and City guidance states plainly that base rent does not reset when ownership transfers.
So the buyer of a covered building steps into the seller's rent history, along with every increase the seller took or skipped since 2020. Two buildings that look the same on a listing sheet can carry very different legal ceilings. A four-unit can also be worth one thing to someone who will live in it and another to someone who won't.
The Number That Transfers With the Deed
Voters approved Portland's rent control ordinance in 2020 and updated it in 2022. It covers rental units across the city, short-term rentals included. Once a unit is covered, its rent can only move through a set of defined channels. Each one has to be documented, and together they can't add up to more than 10% in a year.
Mainebiz reports that the City sets the annual allowance by September 1 each year at 70% of the change in the Greater Boston Metro CPI. The allowance was 2.2% for 2026. On September 1, 2026, the City set the 2027 figure at 2.6%, as the Portland Press Herald reported.
Here are the ways a covered unit's rent can rise heading into 2027:
| Increase channel | How it works | Source of the figure |
|---|---|---|
| Annual allowance | 2.6% for 2027 | City announcement, September 1, 2026 |
| New tenancy | 5% of base rent when a new tenant moves in and the previous tenant left voluntarily | Ordinance |
| Tax-rate adjustment | The actual property-tax increase attributable to that specific unit | City landlord FAQ |
| Banked rent | Allowances a landlord could have taken in past years but did not | Ordinance |
| Rent Board approval | Increases for a fair rate of return, including capital improvements | Case-by-case hearing |
| Ceiling | No more than 10% combined in a year | Ordinance |
Two of these channels matter more to a buyer than they first appear to.
The first is banked rent. A seller who held rents flat for years may have left room that a new owner can use later, still within the 10% annual cap. A seller who raised rents aggressively may have used that room up, or gone past what the ordinance allowed. The rent roll alone won't tell you which.
The second is the tax-rate adjustment. Portland's mill rate went from $11.98 per $1,000 of assessed value in FY2026 to $12.58 in FY2027, according to Mainebiz. That is 60 cents more per $1,000. Under the City's FAQ, though, the pass-through is the tax increase attributable to the individual covered unit, not a blanket percentage on top of rent. On a small building, that usually works out to a modest dollar amount per unit.
Rent Board increases are real, and they get scrutinized. At a December 18, 2024 hearing, the board reviewed a 31-page application for a two-unit on Deering Avenue covering a new boiler, partial roof, water heater, and other work. The board trimmed the requested $543 monthly increase to $505 after questioning a $1,400 leasing-service expense. A buyer counting on capital improvements to reset rents should expect that kind of line-by-line review.
Why the Same Four-Unit Building Has Two Prices
The ordinance exempts units in a landlord-occupied building with two, three, or four dwelling units from its rent-increase limits. The 2020 ordinance text sets the condition as the landlord currently living in one unit as a principal residence. Exempt units still have to be registered.
The exemption depends on who lives in the building, not on the building itself. That changes how the same property pencils out for two different buyers:
- An owner-occupant buying a three-unit can price the two rented units without the annual allowance limiting future increases.
- An absentee investor buying the same three-unit takes on covered units, with base rent that did not reset at the sale.
- Anyone buying five units or more is outside the exemption whether or not they live there, because the exemption stops at four units.
A Portland owner quoted by The West End News in February 2025 described the gap from the owner's side:
"The properties under rent control are wildly under market rate."
That owner, Chris Faulhaber, lives in a four-unit building he owns, which the paper described as exempt from rent control.
The exemption is also tied to the owner continuing to live there. If the owner stops occupying a unit as a principal residence, the condition no longer applies and the rented units fall under the increase limits. City guidance doesn't say what base rent applies when a unit moves from exempt to covered. Anyone planning to live in a building for a few years and then rent all of it should treat that transition as an open question to raise with the City's Housing Safety Office and their own attorney before closing, not as a settled rule.
The Short-Term Rental Table Uses the Same Logic
The City of Portland's amended short-term rental rules, in effect since September 1, 2025, also tie what a building can do to its size and to who lives in it. On the mainland, a two- or three-unit building can have one short-term rental, a four- or five-unit building two, a six- to nine-unit building three, and a building with ten or more units five. The table separately limits how many of those can be non-owner-occupied.
The code closes the obvious workaround. A short-term rental unit in an owner-occupied building that isn't the owner's primary residence counts as non-owner-occupied. New tenant-occupied short-term rental registrations have been barred since January 1, 2026. And rent control applies to short-term rentals too. Under both sets of rules, an owner who lives in the building has more flexibility than one who doesn't.
The City Is Checking the Exemptions
This matters for underwriting because the City actively audits rent control compliance. Staff select properties for audit from several categories, including claimed exemptions such as owner-occupancy, registration forms left blank or filled with zeros, and a random sample for quality control. Housing Safety Manager Zachary Lenhert told The West End News that staff review long-term rental registrations for increases above 10%, and that the office's goal is compliance and getting any money owed back to tenants.
Enforcement is now more of a priority. In September 2026, the City Council voted 7–2 to pass Resolve 02/2627, which directs the city manager and staff to strengthen rent control enforcement and report back on feasibility, budget needs, legal constraints, and any code or budget changes required. More than 40 people commented publicly, and the resolve survived a mayoral amendment that would have sent the whole proposal to the Housing and Economic Development Committee. The resolve doesn't change the ordinance. It does make it more likely that a rent history someone files will actually get looked at.
Reading a Rent Roll Before You Sign
The base rent transfers with the building, so the seller's compliance record transfers with it too. In practice, a buyer can check much of it before closing:
- Look up the registered rents. Rents for non-exempt units are listed in the City's citizen self-service database under "More Info" for each long-term rental license. Compare them to the rent roll the seller provided.
- Rebuild each unit's increase history. The City of Portland's 2026 registration form breaks increases into categories: the annual allowance, the 5% new-tenancy increase, banked rent, and Rent Board-approved increases. Ask the seller for the past filings that show which channels each current rent came through.
- Confirm any claimed exemption. If the seller lists units as owner-occupied exempt, that status leaves with the seller unless you move in and meet the condition yourself.
- Check the notice timeline. The City of Portland requires written notice at least 75 days ahead for rent increases, and a unit's rent can go up only once every 12 months. A closing date can push back the first increase a new owner is able to take.
- Plan the post-closing paperwork. Registration is due within 30 days after an ownership transfer, carries an annual fee of $55 per unit before any applicable discounts, which can reduce it by up to $20 per unit, and expires every December 31. Every property needs an authorized agent, and a business-entity owner has to name an individual who lives in Maine.
None of this replaces legal review. It does turn a rent roll from a marketing document into something you can check against the public record.
Common Questions
Does buying a building reset the rents to market?
No. City guidance says base rent doesn't reset when ownership transfers. A base rent can reset only if a unit has been off the rental market for at least 60 months, or if the Rent Board approves a new base rent after major renovations.
How much can covered rents rise in 2027?
The annual allowance for 2027 is 2.6%, announced September 1, 2026. Other channels can add to it, including the new-tenancy increase, banked rent, the tax-rate adjustment, and Rent Board approvals, but the combined increase can't exceed 10% in a year.
If I live in a four-unit, are my tenants' rents unregulated?
The units are exempt from the increase limits as long as you occupy one as your principal residence. They still have to be registered, and the City audits claimed exemptions. Other state and local rules, including notice requirements and the Maine Human Rights Act, still apply.
If you're weighing a Portland two- to ten-unit building and want the rent history checked against the City's records before you make an offer, Veronica Schneider and the Green Tree Realty team can go through the registrations, exemptions, and increase channels with you as part of underwriting. Schedule a consultation, and bring the rent roll.
This article is general information, not legal, tax or financial advice. Consult a qualified professional about your situation.
