The Residential Tax Exemption under MGL c.59 §5C is in active use by approximately two dozen Massachusetts municipalities — including Boston, Cambridge, Somerville, Brookline, Nantucket, and Provincetown — and under active review by many more. The exemption is revenue-neutral: the residential class pays the same total levy before and after. What changes is who within the class pays more and who pays less. Parcenomics models that shift at every percentage level from 5% to 35% — or up to 50% in qualifying seasonal communities — and shows exactly who benefits and who bears increased burden before your governing body votes.
Policy Moment — April 2026
On April 15, 2026, Mayor Mamdani and Governor Hochul announced New York's first pied-à-terre tax — an annual surcharge on non-primary properties above $5 million. The underlying logic: year-round residents who live, work, and vote here should not carry the full weight of a property tax system shared with wealthy absentee owners who don't.
Boston has been doing a quieter version of this for years. The Residential Tax Exemption saved qualifying FY2026 Boston homeowners up to $4,353 — $351,108 removed from their taxable assessed value at the 35% exemption rate. Brookline saves qualifying owners $3,634. Cambridge $3,403.
Fewer than 24 of Massachusetts' 351 municipalities have adopted the RTE. The communities where it would have the most impact — seasonal towns with 40–60% non-resident ownership — are largely the ones that haven't. Most governing bodies have never modeled what it would mean for their specific community. That is the gap Parcenomics closes.
The formula is simple. The outcome depends entirely on one number: what fraction of your Class 1 residential parcels are owned by year-round residents versus seasonal and non-resident owners.
When most Class 1 parcels don't qualify for the exemption, the rate increase needed to compensate hits a large non-resident base. Year-round residents see substantial savings at a relatively modest rate increase on the non-qualifying parcels.
This is the profile that makes RTE politically viable. The burden shifts away from people who vote in every election, onto owners who have an existing legal obligation to support the community they benefit from.
When most Class 1 parcels qualify for the exemption, the non-qualifying base is thin. The rate must rise significantly to compensate — and at high assessed values, the rate increase on the qualifying parcels can exceed the exemption savings.
This is why the analysis matters before the vote. A community where the seasonal split is low may find that the RTE benefits fewer residents than expected — or actively harms high-value year-round owners.
The law is specific about how the exemption is calculated. Parcenomics applies it at every percentage level and shows the result at the parcel level — not just in aggregate.
Total Class 1 assessed value ÷ total Class 1 parcel count. This is the statutory baseline — the exemption percentage is applied to this average, not to each property's individual value. A fixed dollar amount results — the same for every qualifying parcel regardless of that parcel's assessed value.
Average Assessed Residential Value × governing body's voted percentage (up to 35%, or up to 50% in qualifying communities). This fixed dollar figure is deducted from each qualifying parcel's assessed value. In no case may taxable value fall below 10% of assessed value — the floor constraint matters for lower-value parcels.
Because the exempted value is removed from the taxable base, the residential class rate must increase to raise the same levy. The rate increase is borne entirely by non-qualifying parcels — seasonal owners, investment properties, non-resident owners — who pay the higher rate on their full assessed value.
If a qualifying parcel also carries a personal exemption — Clause 41C for a senior citizen, Clause 22 for a veteran — both apply. Parcenomics checks the 10% taxable value floor on the combined reduction. This interaction materially affects distributional outcomes in communities with significant elderly populations and lower-value housing stock.
The RTE Scenario Matrix shows the exemption amount, new residential rate, and per-household impact for qualifying and non-qualifying parcels at each percentage level.
Example only. Assumes $400,000 AARV, $350,000 median qualifying home, $450,000 median non-qualifying home, 60% qualifying parcel share. Actual output built from your community's specific parcel data.
Massachusetts property tax operates through a layered system of exemptions, classification tools, and overlays. Every layer interacts with the others. Parcenomics is designed to model these interactions — not treat each in isolation.
The RTE analysis produces four specific named documents — plus the exemption integrity review that runs as part of the compliance infrastructure.
Every percentage from 5% to the applicable statutory maximum. For each: exemption dollar amount, new residential rate, qualifying and non-qualifying parcel counts, median savings for qualifying parcels, median increase for non-qualifying parcels, and parcel-level floor constraint analysis. Formatted for both technical review and plain-language presentation to elected officials.
The complete cross-referenced list of Class 1 parcels classified as qualifying (resident-owned) or non-qualifying (non-resident/seasonal). This is the parcel-level foundation of the scenario matrix — and the same data that drives the Compliance Review's PPT non-payer screen. Produced as part of the shared data infrastructure.
A plain-language summary showing what the RTE means for four representative households: the median year-round resident, the lower-value year-round resident (floor constraint analysis), the median seasonal owner, and the high-value year-round resident (rate increase may exceed exemption savings). This is the document your board or council members will be asked about when constituents call the day after the vote.
Non-resident parcels currently receiving residency-tested personal exemptions — veteran, senior, surviving spouse, blind — flagged for assessor review. Includes the estate transition watch list: parcels where the owner has likely died based on voter roll signals, with residency-tested exemptions at risk. The legal basis for each flag is explicitly cited.
Your municipality has the data. It just exists in different silos. Parcenomics synthesizes these data sets, verifies them against state statutes and formulas, and produces analytical options for your leaders to consider.
The Compliance Review builds the Non-Resident Owner universe by cross-referencing voter rolls and the annual street listing (MGL c.51 §4 — the full census of residents, not just voters) against the assessor's parcel database. This is exactly the data required to determine which Class 1 parcels are resident-owned (qualifying for the RTE) and which are non-resident or seasonal (non-qualifying).
If you've already run the Compliance Review, the qualifying/non-qualifying split for the RTE analysis is already done. The RTE scenario matrix runs on infrastructure that exists. The marginal cost of adding the RTE analysis to a Compliance Review engagement is substantially lower than starting from scratch.
Rate Classification shifts burden between property classes — residential vs. commercial vs. industrial. The RTE shifts burden within the residential class — resident-owned vs. seasonal/non-resident.
A Select Board or City Council can do both simultaneously. A community that adopts a residential factor below 1.0 under MGL c.40 §56 and simultaneously adopts the RTE under MGL c.59 §5C is using two statutory tools to achieve a combined result: reducing the overall residential class burden and ensuring that reduction flows primarily to year-round residents rather than seasonal owners.
No one else is currently modeling that combined interaction. Parcenomics does.
A modest engagement fee covers data access setup and delivery of your Revenue Opportunity Assessment — which for an RTE engagement includes a preliminary qualifying/non-qualifying split estimate and initial scenario preview.
Your first deliverable. Shows the likely qualifying split, the range of outcomes at the most common exemption percentages, and outlines the full deliverable set with corresponding fees. You see the picture before committing.
Each named document carries its own fee, billed on delivery. Substantially reduced when added to an existing Compliance Review engagement — the residency cross-reference infrastructure is already built.
The qualifying/non-qualifying split is the number that determines everything — and it's the number most communities have never had. We can estimate it from a single conversation about your community's profile before you commit to anything.
Contact Us