Cost Segregation Study in Massachusetts for Airbnb and Short-Term Rental Investors

Massachusetts has decoupled from federal bonus depreciation since Technical Information Release 02-11 (2002) and TIR 03-25 (2004), and that position has not changed with the One Big Beautiful Bill Act (OBBBA). Massachusetts's published guidance on differences between state and federal tax law confirms that IRC Section 168(k) bonus depreciation continues to be disallowed, and DOR has applied the same add-back-and-recover approach to personal income tax filers under M.G.L. c. 62, § 1, with the corresponding corporate excise provision at M.G.L. c. 63, § 30(4) extended by successive DOR guidance to each later round of bonus depreciation beyond the original 2002-2004 rules. A Massachusetts taxpayer who claims federal bonus depreciation must add that amount back to Massachusetts gross income in the year it's taken, then recover the added-back basis on a straight-line basis over the asset's regular MACRS recovery period on the state return. The Department of Revenue's June 23, 2026 release, TIR 26-4, addressing conformity to the OBBBA (Public Law No. 119-21), addresses how Massachusetts treats the law's various depreciation-related provisions; consistent with the state's longstanding position, standard bonus depreciation ("full expensing") under Section 168(k) is not allowed to flow through to the Massachusetts return, though Massachusetts does conform to certain narrower OBBBA depreciation items (such as increased Section 179 limits and the new allowance for qualified production property) — taxpayers should review TIR 26-4 directly for provision-specific detail before filing, since this is a legislative add-back mechanism, not a reflexive rolling conformity to whatever Congress does with Section 168(k).

That matters less than it sounds like for cost segregation, because the core value of a study isn't the bonus percentage — it's correctly identifying which components of a building qualify for 5-, 7-, or 15-year lives instead of being lumped into 27.5- or 39-year real property. Massachusetts still allows straight-line depreciation over those shorter class lives, so a $150,000 chunk of site improvements and personal property that a study pulls out of a 39-year commercial building still depreciates over 15 years (or 5 and 7) for Massachusetts purposes — dramatically faster than if it had stayed folded into the building's real property basis, bonus or no bonus.

Property values reinforce the case. Per the Massachusetts Department of Revenue's Division of Local Services property tax data, the statewide average effective property tax rate runs roughly 1.1% to 1.2% of assessed value, and because home and building values across the Boston metro, Cambridge, and the Cape and Islands run well above the national median, actual tax bills are high in dollar terms — median annual homeowner tax bills across the state generally fall in the roughly $5,800 to $6,700 range depending on the year and municipality mix. Larger property values generally mean a larger depreciable basis to segregate, and with the state's own income tax running 5% flat (9% for income above the surtax threshold), every dollar of accelerated depreciation — federal or state — still offsets real tax liability.

Under standard IRS depreciation rules, an entire residential rental building is written off in equal amounts over 27.5 years, and a commercial building over 39 years — regardless of the fact that a roof, a parking lot, cabinetry, and a HVAC system don't actually wear out on the same schedule as the building's structural shell. A cost segregation study is an engineering-based analysis, typically performed with a site visit, blueprints, and construction cost data, that separates a property's total cost basis into its component parts and assigns each one the depreciation life the IRS actually allows for it — 5 years for items like appliances, certain flooring, and decorative fixtures, 7 years for furniture and other tangible personal property, and 15 years for land improvements such as driveways, fencing, and landscaping. On the federal return, the One Big Beautiful Bill Act, signed into law in July 2025, permanently restored 100% bonus depreciation for qualifying property with a recovery period of 20 years or less that is acquired after January 19, 2025, meaning everything the study reclassifies into the 5-, 7-, and 15-year buckets can potentially be deducted in full in the placed-in-service year at the federal level. Massachusetts does not allow that immediate federal write-off to pass through to the state return — see the section above — but the underlying reclassification still shortens the state depreciation schedule.

For illustration only — your results depend on your property and tax situation, and this is not a projection of actual savings.

Suppose an investor purchases a short-term rental cottage near Barnstable on Cape Cod for $850,000, with $200,000 allocated to land and $650,000 to the building and site. A cost segregation study might identify roughly 25-30% of that $650,000 building basis — about $180,000 — as 5-, 7-, and 15-year property (furnishings, decking, outdoor lighting, driveway, and similar components), rather than the standard 27.5-year residential rental schedule. At the federal level, under the current 100% bonus depreciation rules for property acquired after January 19, 2025, that $180,000 could potentially be deducted in the year the property is placed in service, which at an illustrative 32% federal marginal rate would represent roughly $57,600 of federal tax deferral in year one — again, illustrative only, not a guarantee. On the Massachusetts return, that same $180,000 would be added back and instead recovered on a straight-line basis over the applicable 5-, 7-, and 15-year lives — still notably faster than depreciating it over 27.5 years, just spread out rather than taken all at once.

Cost segregation isn't limited to the year of purchase. If you've owned a Massachusetts rental property for several years without ever segregating its cost basis, you don't need to amend prior tax returns to capture the missed depreciation. A "look-back" study identifies what should have been classified as 5-, 7-, or 15-year property from the original placed-in-service date, and the accumulated difference between what was actually depreciated and what should have been depreciated is claimed in the current year using IRS Form 3115, Application for Change in Accounting Method. The resulting adjustment is reported under Section 481(a) as a single catch-up deduction in the year the change is filed — a mechanism designed specifically so that owners of long-held rental property, whether a Somerville duplex or a Nantucket vacation home, can still benefit from a study conducted well after closing.

• Short-term rental and Airbnb hosts in Cape Cod towns such as Barnstable, Provincetown, Chatham, and Falmouth, as well as on Nantucket and Martha's Vineyard, where nightly rates and seasonal demand are among the highest in New England
• Berkshires vacation property owners in towns like Lenox and Great Barrington, where cultural tourism around Tanglewood and nearby ski areas supports a steady short-term rental market
• Long-term rental owners with multifamily buildings in Boston, Cambridge, Somerville, and Worcester, where high property values translate into a large depreciable basis
• Recent buyers or owners who just completed a renovation or buildout, since a study captures the largest benefit when done close to acquisition or construction completion
• High-income owners exploring the short-term rental material participation strategy, who may be able to use STR losses to offset active W-2 or business income if they meet the IRS's average-stay and material-participation tests