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Cost Segregation · Connecticut

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

Connecticut is one of the relatively small number of states that does not let individual and pass-through property owners take the full federal bonus depreciation deduction in the year they claim it on their state return.

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Connecticut is one of the relatively small number of states that does not let individual and pass-through property owners take the full federal bonus depreciation deduction in the year they claim it on their state return. Under Conn. Gen. Stat. § 12-701(a)(20), a Connecticut resident (or nonresident with Connecticut-source rental income) who claims bonus depreciation under IRC § 168(k) must add that amount back to Connecticut adjusted gross income in the year it is taken, then recover it in even 25% installments over each of the following four tax years. That mechanism matters enormously for cost segregation, because a study's entire value comes from reclassifying building components into short-lived asset classes eligible for bonus depreciation — Connecticut does not erase that benefit, but it does change when you feel it on your state return, even as the full deduction still reduces your federal taxable income immediately.

Apex Reserve Group, based in Irvine, California, prepares engineering-based cost segregation studies for real estate investors nationwide, including short-term rental and long-term rental owners throughout Connecticut. This page is general educational information, not tax or legal advice — every owner's facts differ, and you should confirm how the Connecticut add-back and any planning strategy apply to your specific return with a qualified CPA or tax attorney before filing.

Why Cost Segregation Pays Off in Connecticut

Connecticut generally follows federal adjusted gross income as the starting point for its own income tax, but the legislature carved out bonus depreciation specifically. Public Act 18-49, codified at Conn. Gen. Stat. § 12-701(a)(20), requires an addition modification equal to any bonus depreciation deduction claimed under IRC § 168(k) for property placed in service after September 27, 2017 — and then allows the taxpayer to subtract 25% of that added-back amount in each of the four succeeding tax years. In other words, Connecticut spreads recognition of the bonus-depreciation benefit over five tax years (the add-back year plus four recovery years) instead of disallowing it outright. Because this add-back attaches to IRC § 168(k) generally rather than to a specific percentage or a specific federal tax act, it is reasonable to expect it to apply to the 100% bonus depreciation the One Big Beautiful Bill Act (OBBBA) restored for property acquired after January 19, 2025 — Connecticut's legislature has not amended § 12-701(a)(20) to say otherwise. That said, as of mid-2026 the Connecticut Department of Revenue Services had not published an OBBBA-specific personal income tax notice confirming this treatment (its published 2026 developments page addresses only Corporation Business Tax changes), so owners should confirm current-year treatment with DRS guidance or a Connecticut CPA before relying on it. State conformity to federal bonus depreciation has been a recurring topic in past Connecticut legislative sessions, but no change to § 12-701(a)(20) had been enacted as of mid-2026.

What this means practically: a Connecticut rental owner who does a cost segregation study still gets the full federal first-year deduction against federal taxable income, and Connecticut's personal income tax (a graduated tax running from 2.00% up to 6.99%) simply recaptures that acceleration on a four-year glide path rather than a one-year hit. For an investor who plans to hold and keep depreciating, that spread-out add-back is manageable cash-flow-wise and still leaves the federal savings, plus faster depreciation of components with genuinely short useful lives (carpet, appliances, site work, fencing, driveways), largely intact.

Property taxes add a second reason cost segregation studies get attention in Connecticut. The state carries one of the highest average effective property tax burdens in the country — estimates range from about 1.54% of home value (Tax Foundation) to about 1.81% (WalletHub), with enormous local variation. Local mill rates are not directly comparable to these percentage figures, however, because Connecticut towns assess property at 70% of appraised value — Hartford's 68.95 mill FY2025–26 rate, for example, works out to an effective rate near 4.8% of market value once that 70% assessment ratio is applied, while rural towns like Washington, with a mill rate closer to 11, carry a much lower effective burden. Because a cost segregation study produces a defensible, engineering-based allocation of a property's purchase price between land, building shell, and short-life components, it can also give an owner better documentation to support the building-versus-land split used in assessment appeals or basis calculations, separate from its core depreciation benefit.

How a Cost Segregation Study Works

Without a study, the IRS default is to depreciate an entire residential rental building on a straight-line basis over 27.5 years, or a commercial building over 39 years, treating the structure as one undifferentiated asset. A cost segregation study is an engineering-based analysis — typically performed with a site visit, cost documentation review, and IRS-recognized methodology — that separates a property into its individual components and assigns each one the depreciable life the tax code actually allows it. Items like flooring, cabinetry, certain electrical and plumbing dedicated to appliances, decking, landscaping, and paving are often reclassified into 5-, 7-, or 15-year asset classes rather than lumped into the 27.5- or 39-year bucket. Under the One Big Beautiful Bill Act, signed into law on July 4, 2025, qualifying property acquired and placed in service after January 19, 2025 is again eligible for 100% federal bonus depreciation, meaning those reclassified 5-, 7-, and 15-year components can potentially be deducted in full in the year the property is placed in service, rather than depreciated gradually over their assigned life.

A Connecticut Cost Segregation Example

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 $650,000 short-term rental cottage near Mystic, allocating roughly $500,000 to the depreciable building (after backing out land value). Under standard straight-line depreciation, that $500,000 would be written off over 27.5 years, or about $18,000 per year. A cost segregation study might reclassify somewhere around 20-30% of that basis — for illustration, roughly $125,000 — into 5-, 7-, and 15-year property. Under current federal bonus depreciation rules, that reclassified portion could potentially be eligible for a substantial first-year deduction at the federal level. On the Connecticut return, the owner would add back the federal bonus depreciation claimed and then recover 25% of that add-back in each of the next four tax years under Conn. Gen. Stat. § 12-701(a)(20) — a real difference in state-return timing that a CPA should model against the owner's specific bracket and holding plan before the study is commissioned.

Already Own Your Connecticut Property? The Look-Back Study

Investors are sometimes surprised to learn that a cost segregation study is not limited to the year of purchase. If you already own a Connecticut rental — whether it's been in service for two years or twelve — a look-back study can still identify the same 5-, 7-, and 15-year components that should have been separated out from day one. Rather than filing amended returns for every prior year, the mechanism used is IRS Form 3115, Application for Change in Accounting Method, paired with a Section 481(a) adjustment. That adjustment lets you claim the cumulative depreciation you missed in earlier years as a single catch-up deduction in the current tax year, without reopening or amending past filings. For a Connecticut owner, that catch-up deduction would flow through the same state add-back and four-year recovery mechanism described above in the year it's claimed.

Who Should Consider Cost Segregation in Connecticut

  • Short-term rental and Airbnb hosts operating in Connecticut's established vacation markets, including Mystic and the Litchfield Hills around Lake Waramaug and Mohawk Mountain
  • Owners of shoreline vacation rentals along the Connecticut coast in towns such as Madison, Westbrook, and Clinton, where seasonal demand from New York and Boston visitors supports strong booking activity
  • Long-term rental property owners in Connecticut's larger rental markets, including Hartford, New Haven, Stamford, Bridgeport, and Old Saybrook (Old Saybrook's zoning code prohibits short-term rentals of single-family homes and accessory apartments for stays under 30 days, so confirm local zoning before assuming nightly-rental use there)
  • Recent buyers or owners who have completed a substantial renovation, since both new acquisitions and major improvements create fresh basis to analyze
  • High-income W-2 earners or business owners considering the short-term rental material participation strategy, which can allow STR losses to offset active income when average guest stays are seven days or less and material participation tests are met
  • Owners weighing the timing effect of Connecticut's bonus depreciation add-back and four-year recovery period as part of a multi-year tax plan

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FAQs

Connecticut questions, answered.

Does Connecticut conform to federal bonus depreciation?

No, not in the same year. Connecticut requires individual and pass-through taxpayers to add back federal bonus depreciation claimed under IRC § 168(k), per Conn. Gen. Stat. § 12-701(a)(20), for property placed in service after September 27, 2017. The taxpayer then recovers 25% of that added-back amount in each of the next four tax years. This is expected to apply to the 100% bonus depreciation restored by the OBBBA in the same way it applied to earlier bonus depreciation rules, since the add-back is tied to IRC § 168(k) itself — though as of mid-2026 DRS had not published OBBBA-specific personal income tax guidance confirming this, so confirm current-year treatment with DRS or a CT CPA. The federal deduction is not lost either way — Connecticut just changes the timing of when you see the benefit on your state return.

Is cost segregation worth it for a Connecticut short-term rental?

It can be, particularly in established vacation markets like Mystic and the Litchfield Hills where properties often carry substantial improvement and furnishing costs alongside the building itself. A study identifies which components qualify for shorter depreciable lives and, potentially, first-year bonus depreciation at the federal level. Because Connecticut spreads the state-level benefit over five years via its add-back mechanism rather than eliminating it, the analysis usually still favors doing the study for owners who plan to hold the property and want the federal acceleration — but the exact math depends on your income, filing status, and holding period, so it should be modeled with a CPA. Note that some Connecticut towns, including Old Saybrook, restrict short-term rentals under 30 days by zoning, so confirm local rules before assuming nightly-rental use.

I already own my Connecticut rental property — can I still do a cost segregation study?

Yes. A look-back study can be performed on a property you've owned for years, not just one you recently purchased. Instead of amending past tax returns, your CPA files IRS Form 3115 with a Section 481(a) adjustment, which lets you claim the depreciation you missed in prior years as a single catch-up deduction in the current year. That catch-up amount would then flow through Connecticut's standard bonus depreciation add-back and four-year recovery treatment in the year it's claimed.

What is the short-term rental material participation strategy, and does it work in Connecticut?

The strategy relies on federal tax rules: if a rental's average guest stay is seven days or less and the owner materially participates in operating it, the activity can be treated as a trade or business rather than a passive rental for federal purposes, which may allow losses (including those generated by cost segregation and bonus depreciation) to offset active income like W-2 wages. This is a federal mechanism, so it can apply to a qualifying Connecticut short-term rental just as it would elsewhere, provided local zoning permits that use. Connecticut's separate bonus depreciation add-back still applies to the state return regardless of how the activity is classified federally, so the state-level timing effect described above remains relevant. This strategy involves detailed material participation and record-keeping requirements and should be reviewed with a CPA before relying on it.

How much can I save with a cost segregation study on my Connecticut property?

There is no fixed percentage or dollar figure that applies to every property — savings depend on the purchase price, the building-to-land allocation, the age and type of construction, your income and filing status, and how Connecticut's add-back and four-year recovery rule interacts with your specific return. Any example on this page is illustrative only and not a projection of actual results. An engineering-based study followed by a review with a qualified CPA or tax attorney is the only way to know what a specific Connecticut property could generate.

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