Cost Segregation Study in Connecticut
Connecticut is unusual in that its two income taxes treat depreciation differently. The personal income tax starts from federal adjusted gross income and therefore carries federal bonus depreciation through with no adjustment. The corporation business tax adds it back and gives it back over four years.
For the individual investor or pass-through owner, that means a Connecticut cost segregation study delivers both a federal and a state deduction in the same year. That is a better outcome than New York, New Jersey, or Massachusetts offer, and it is not widely understood.
How Connecticut Income Tax Interacts With Federal Strategy
Connecticut's personal income tax is graduated with a top rate of 6.99%. Connecticut applies a benefit recapture that phases out the benefit of the lower brackets for higher earners, so the effective marginal rate at certain income levels exceeds the nominal top rate. There is no preferential rate for capital gains.
The corporation business tax is 7.5% of net income, and a 10% surcharge applies to larger corporations, which has been extended repeatedly. There is also a capital base tax alternative and a minimum tax.
The key structural fact is that Connecticut computes personal taxable income starting from federal adjusted gross income with a limited list of additions and subtractions. Bonus depreciation is not on the addition list for individuals, so it flows through. This is why the same investor gets a materially different answer in Connecticut than in New York.
Connecticut Pass-Through Entity Tax
Connecticut was the first state in the country to enact a pass-through entity tax, in 2018, and for several years it was mandatory rather than elective. Legislation effective for tax years beginning on or after January 1, 2024 made the tax elective, aligning Connecticut with the rest of the country.
Under the current regime, an electing partnership or S corporation pays 6.99% on its Connecticut source income, deducts the payment federally, and the owners claim a credit against their Connecticut personal income tax. The credit percentage has changed over the life of the statute, and the current design restores a fuller credit than the reduced version that applied in the mandatory years.
Because the tax is now elective, Connecticut owners have to affirmatively decide each year. Owners who were on autopilot during the mandatory years sometimes miss the election entirely and lose the federal deduction, which is a costly clerical failure in a 6.99% state.
For an owner with $1 million of Connecticut source pass-through income, the election converts roughly $70,000 of state tax from a capped itemized deduction into a fully deductible entity-level expense, worth about $26,000 of federal tax at the top rate.
Connecticut Depreciation Conformity
For personal income tax purposes Connecticut allows federal bonus depreciation, because Connecticut taxable income begins with federal adjusted gross income and Connecticut does not require an addback for individuals. A cost segregation study on a property held individually or through a pass-through entity therefore reduces Connecticut taxable income in the same year it reduces federal taxable income.
For corporation business tax purposes Connecticut decouples. Corporations add back the federal bonus depreciation deduction and are permitted to deduct 25% of the addback in each of the four succeeding income years. Connecticut also requires an addback related to federal Section 179 expensing with a similar multiyear recovery.
That split means the entity structure drives the Connecticut answer. The same building generating an accelerated deduction produces an immediate Connecticut benefit inside an LLC taxed as a partnership and a four year deferred benefit inside a C corporation. In Connecticut, entity choice and depreciation strategy are the same conversation.
Cost Segregation Considerations Specific to Connecticut
The first Connecticut consideration is that the individual conformity makes the study unusually attractive. A $1 million Connecticut property with a 25% reclassification produces roughly $250,000 of accelerated deduction. For a top-bracket owner that is about $92,500 federally plus roughly $17,500 in Connecticut, in the same year, with no addback schedule to carry.
The second is that Connecticut generally follows the federal passive activity loss rules, so usability turns on material participation exactly as it does federally. The seven day average stay rule that removes short-term rentals from the definition of a rental activity applies in the Connecticut analysis by virtue of the federal AGI starting point.
The third is the corporate four year spread. Connecticut C corporations should model the addback recovery against expected holding period, because a disposition inside four years leaves part of the addback unrecovered at the time of sale.
The fourth is the state's high property values in Fairfield County and along the shoreline. Connecticut studies frequently involve properties above $1.5 million where the reclassification percentage on a well built residential property runs at the upper end of the range, and where the fixed cost of the study is a small fraction of the benefit.
Working With AE Tax Advisors in Connecticut
AE Tax Advisors works with real estate investors, business owners, and high-income professionals across Connecticut and all fifty states. We are a licensed CPA and IRS Enrolled Agent practice, and we handle the engineering-based cost segregation study, the Connecticut conformity analysis, the pass-through entity tax election, and the return preparation as one engagement.
Connecticut rewards getting the entity question right before the study rather than after. We model the federal and Connecticut outcome under the actual ownership structure, and where a change in structure produces a better Connecticut answer we say so before the money is spent.
Related reading: the complete guide to cost segregation, our cost segregation study service, short-term versus long-term rental tax treatment, lookback studies and Form 3115, and multi-state tax planning.
Connecticut Cost Segregation and Tax Questions
Does Connecticut allow bonus depreciation?
For personal income tax purposes, yes. Connecticut taxable income starts from federal adjusted gross income and Connecticut does not require individuals to add back the IRC Sec. 168(k) deduction. For corporation business tax purposes Connecticut decouples: corporations add back the federal bonus deduction and recover 25% of it in each of the four succeeding income years.
Is the Connecticut pass-through entity tax still mandatory?
No. Connecticut's PTET was mandatory from 2018 through 2023 and became elective for tax years beginning on or after January 1, 2024. Owners who were accustomed to the mandatory regime need to affirmatively make the election each year, and missing it forfeits the federal deduction for that year.
Is cost segregation worth it in Connecticut?
Frequently yes, and Connecticut is more favorable than its neighbors for individual owners because the state allows the bonus deduction to flow through from federal AGI. A top-bracket Connecticut owner captures both the federal deduction and roughly 6.99% of state benefit in the same year with no addback schedule.
What is Connecticut's corporate tax rate?
The corporation business tax is 7.5% of net income, with a 10% surcharge applying to larger corporations that the legislature has extended repeatedly. A capital base tax and a minimum tax also apply, and Connecticut corporations face a four year recovery on the bonus depreciation addback.
Does Connecticut follow the federal passive activity loss rules?
Effectively yes for individuals, because Connecticut begins with federal adjusted gross income, which already reflects the IRC Sec. 469 limitations. Whether a rental loss is usable in Connecticut therefore turns on the same material participation analysis that governs the federal result, including the seven day average stay rule for short-term rentals.
Book a Connecticut Tax Strategy Call
Pick a time below. We will walk through your Connecticut property or business, model the federal and Connecticut outcome side by side, and tell you plainly whether a study is worth running.
Connecticut tax rates, pass-through entity tax rules, and depreciation conformity provisions described on this page reflect law in effect as of August 2026 and are provided for general information only. State conformity changes frequently and often retroactively. Nothing here is tax advice for your situation, and no client relationship is created by reading it. Talk to us about your facts before acting.