Buying a Vacation Rental on Cape Cod: The Tax Stack Generic STR Guides Miss

Massachusetts' Statewide STR Law, in Full

Every short-term rental in Massachusetts, Cape Cod included, operates under Chapter 337 of the Acts of 2018, with most provisions effective July 1, 2019. The law requires anyone operating a short-term rental to register for a certificate of registration through the Massachusetts Department of Revenue, which in turn creates a statewide public registry of short-term rental units - though the published registry limits an individual listing's address to street and municipality rather than the full street address, so it functions as public disclosure without pinpointing a specific home.

On the tax side, the law imposes a 5% state room occupancy excise on short-term rental transfers. Two exemptions matter for anyone underwriting a Cape Cod purchase: rentals charging under $15 per day are exempt outright, and a host who rents a property for 14 days or fewer per year can file a declaration of exemption to avoid the tax entirely - relevant if you're weighing occasional owner use plus a handful of rented weeks against a full-season rental operation. On top of the 5% state excise, a municipality may add a local option excise of up to 6% (6.5% specifically in Boston, which has no bearing on any Cape town). Whether and how much of that local-option excise a specific Cape town has actually adopted is a rate to confirm town by town - it is not uniform across the Cape's fifteen towns by default.

The Cape-Specific Wrinkle: A 2.75% Water Protection Fund Excise on Top

This is the fact that generic, national short-term-rental-law explainers miss entirely, and it is the single biggest reason a "5% plus local option" summary understates what a Cape Cod STR owner actually pays. Municipalities in Barnstable, Dukes, and Nantucket Counties - that is, Cape Cod and the Islands - are automatically subject to an additional 2.75% excise, the Cape Cod and Islands Water Protection Fund, layered on top of the state and local rates described above. It exists to fund coastal water-quality and wastewater infrastructure, a genuinely regional cost tied to the Cape's well-documented nitrogen-loading and septic-system pressures on its coastal waters and estuaries.

Add the three layers together and the total possible STR excise exposure on a Cape Cod rental can run as high as roughly 5% (state) + 6% (maximum local option) + 2.75% (Water Protection Fund) = approximately 13.75%, depending on the specific town's local-option rate. That is a materially higher stacked tax burden on gross short-term rental receipts than a reader would expect from any national "here's how STR taxes work" article, none of which account for the Cape-and-Islands-specific water fund layer. Before modeling gross rental income into a pro forma, confirm the actual local-option rate the specific town has adopted - it may sit well below the 6% ceiling - and treat the 2.75% Water Protection Fund excise as a fixed, non-negotiable addition on top of whatever that town-level rate turns out to be.

The Insurance Requirement Homeowners Policies Don't Cover

Beyond registration and tax, Chapter 337 requires STR operators to carry a minimum of $1,000,000 in liability insurance, unless the hosting platform used to book the property already provides equivalent coverage. This is not a minor compliance checkbox: standard homeowners insurance policies typically exclude short-term rental activity altogether, meaning a policy that would otherwise cover the home for ordinary owner-occupied use may not respond to a claim arising from a paying guest's stay. Anyone evaluating a Cape Cod home for rental income needs to price this in as a real, recurring cost of doing business - either a dedicated short-term-rental liability policy or verified confirmation that the booking platform's own coverage genuinely meets the $1,000,000 minimum - rather than assuming an existing homeowners policy already has it covered.

The Acquisition Side: CCIAOR's 2025 Numbers and the Town-to-Town Spread

Tax exposure is only half of an investment equation - the other half is what you pay to buy in. The Cape Cod & Islands Association of Realtors' full-year 2025 MLS data is the most authoritative region-wide source available: median single-family price of $790,000 (up from $765,000 in 2024) and median condo price of $494,500 (down from $517,500 in 2024), across 3,507 total homes sold. Sellers received 95.2% of original asking price on average, with days on market rising to 58 for single-family homes and 52 for condos, and roughly 2.0 months of supply - a market that has cooled somewhat from its tightest years but remains a seller-favorable one.

That region-wide median flattens a genuinely dramatic town-to-town spread worth knowing before you shop by neighborhood. CCIAOR's own town-level data puts Chatham's 2025 median sale price at $1,500,000 and Yarmouth's at $589,000. A separate, less rigorously sourced real-estate-agent market report from May 2026 illustrates the same spread with figures including Dennis around $526,000 on the low end up through Chatham around $1,465,000 on the high end - roughly a 2.5x-2.8x difference in acquisition cost within a single county, before a dollar of rental income enters the picture. Which end of that spread you buy into changes both your entry cost and the rental rate a given town's market can support, so treat any single "Cape Cod median" figure - including the ones in this section - as a starting point for comparison, not a number to plug directly into a purchase decision for a specific town.

The Honest Gap: No Rental-Performance Data Here

This research was built to document the region's STR regulatory and tax framework in depth - the state law, the Cape-specific water fund stacking, the insurance requirement, and the realtor association's own price data. It did not gather platform-level rental-performance data for Cape Cod: no occupancy rates, no average daily rates, and no listing counts from AirDNA, Rabbu, AirROI, or similar short-term-rental analytics platforms, for the region as a whole or for any individual town. That kind of data changes quickly, varies enormously by town and even by neighborhood within a town, and simply was not the focus of this pass of research.

If you need current rental-income numbers to actually underwrite a purchase, go to those platforms directly for a specific address or town, or - likely the more useful path for a market this locally variable - talk to a property manager who already operates rentals on Cape Cod in the specific town you're considering. A local manager can tell you what a comparable home in that neighborhood actually grossed last season, what the realistic occupancy looks like across shoulder season versus peak summer, and how the property tax stacking described above nets out against real bookings - none of which this page can responsibly estimate without inventing numbers it doesn't have.

Before You Buy for Rental Income

Confirm the current STR registration requirement and process with the Massachusetts Department of Revenue, and confirm the specific town's local-option excise rate directly with that town before assuming any figure in this page still holds - local rates can change, and this page states a maximum (6%) and a fixed Cape-and-Islands addition (2.75%), not a single confirmed number for every town. Some Cape towns have also adopted their own additional zoning-based short-term-rental restrictions beyond the statewide registration and tax law - rules on owner-occupancy, rental caps, or permitted zoning districts that this region-wide research did not catalog town by town. Ask the specific town's planning or zoning office directly whether any such local restriction applies before assuming a property can legally operate as a short-term rental at all.

Nothing on this page is financial, tax, or legal advice. Between the stacked excise exposure, the $1,000,000 insurance requirement, the wide town-to-town swing in acquisition cost, and the rental-performance data this page deliberately does not estimate, a Cape Cod rental purchase deserves direct confirmation from the town, the Massachusetts Department of Revenue, a local property manager, and a CPA or attorney before you commit to buying for rental income.