The biggest 2027 change for cost segregation is that qualified property acquired on or before January 19, 2025 and placed in service in 2027 gets 0% bonus depreciation under IRC §168(k), with narrow exceptions, while qualified property acquired after January 19, 2025 (a date generally set by the written binding contract, not the closing) keeps 100% bonus permanently.
The exceptions are long-production-period property and certain aircraft, which keep 20% for 2027 (long-production-period property only on basis from work before 2027). Much of cost segregation does not change in 2027: the study still moves eligible basis out of the 27.5-year residential rental or 39-year nonresidential real property shell under §168(c) into 5-, 7- and 15-year property, the placed-in-service test is the same, and a study accelerates deductions rather than adding basis, so over the life of the building the same basis is recovered. What changes is the bonus rate for older acquisitions, which return a late-2026 or early-2027 completion lands on, the correction route for a property placed in service in 2026 and filed without a study, and a set of 2027 figures the IRS had not published when this was written.
What changes for cost segregation in 2027?
In 2027, cost segregation planning changes in four ways: qualified property acquired on or before January 19, 2025 and placed in service in 2027 gets 0% bonus depreciation, a calendar-year taxpayer's 2027 placements go on the 2027 return, a 2026 property filed without a study gains a second correction route, and a new Opportunity Zone map takes effect. Each one depends on the condition stated with it below:
- Bonus for older acquisitions reaches 0%. Qualified property acquired on or before January 19, 2025 (or self-constructed property whose construction began on or before that date) and placed in service in 2027 gets 0% bonus depreciation, against 20% if placed in service in 2026, except long-production-period property and certain aircraft, which keep 20% for 2027 under §168(k)(6)(B) as enacted by the Tax Cuts and Jobs Act (long-production-period property only on its basis attributable to construction or production in 2026 or earlier, under §168(k)(2)(B)(ii) as in effect before OBBBA).
- The placed-in-service year decides the return. For a calendar-year taxpayer, property placed in service (ready and available for its intended use) on or after January 1, 2027 is first depreciated on the 2027 return.
- A 2026 property filed without a study has two routes. For a calendar-year taxpayer that placed property in service in 2026 and depreciated it on one filed 2026 return, the missed cost segregation depreciation can be claimed on Form 3115 with the 2027 return (when the taxpayer still owned the property at the start of 2027 and meets the other eligibility rules), or on an amended 2026 return filed before the 2027 return is filed.
- A new Opportunity Zone map takes effect. The new zones Treasury designates take effect January 1, 2027, which matters only for a project in a designated tract held through a qualified opportunity fund.
Does property placed in service on December 31, 2026 or in January 2027 go on a different return?
For a calendar-year taxpayer, property placed in service (ready and available for its intended use) by December 31, 2026 is first depreciated on the 2026 return, and property placed in service on January 1, 2027 or later is first depreciated on the 2027 return, while a fiscal-year taxpayer uses the end of its own tax year instead. Property is placed in service when it is ready and available for its specifically assigned function under Treas. Reg. §1.46-3(d)(1)(ii), so for a rental it is the date the property is ready and available to rent, not the closing date or the first move-in, and the calendar-year guide to rental property placed in service by December 31 covers how to document it.
The convention changes how much of the first year a late-2026 or early-2027 date earns. Under §168(d)(2), the 27.5-year and 39-year shell always uses the mid-month convention, so a shell placed in service in December 2026 earns one-half month of regular depreciation on a calendar-year taxpayer's 2026 return, and a shell placed in service in January 2027 earns eleven and a half months on the 2027 return.
The 5-, 7- and 15-year property a cost segregation study identifies generally uses the half-year convention under §168(d)(1), unless more than 40% of the aggregate basis of property placed in service during the year (not counting residential rental and nonresidential real property) was placed in service in the last three months of the tax year, in which case the mid-quarter convention applies under §168(d)(3). The mid-quarter convention and fourth-quarter property guide works through that test, and the convention does not reduce bonus depreciation on the basis that takes it.
The placed-in-service date follows the facts of when the property was ready and available; it is not a date an owner or a study can choose on paper, and no property should be bought or rushed into service for the deduction alone.
What bonus depreciation rate applies to cost segregation property placed in service in 2027?
Bonus depreciation under IRC §168(k) is 100%, permanently, for qualified property acquired after January 19, 2025 (OBBBA, 2025-07-04), or, for self-constructed property, whose construction began after that date; qualified property acquired on or before that date stays on the TCJA phase-down (as does self-constructed property begun on or before it) by placed-in-service year: 80% in 2023, 60% in 2024, 40% in 2025, 20% in 2026, and 0% after that, with each rate one year later for long-production-period property and certain aircraft (§168(k)(6)(B)). For long-production-period property placed in service in 2027, that one-year-later 20% under §168(k)(6)(B) as enacted by the Tax Cuts and Jobs Act applies only to its basis attributable to construction or production in 2026 or earlier (§168(k)(2)(B)(ii) as in effect before OBBBA); that basis limit does not apply to the aircraft described in §168(k)(2)(C).
That makes 2027 the first year in which a building placed in service after a construction start on or before January 19, 2025 gets no bonus depreciation on the 5-, 7- and 15-year property its cost segregation study identifies, except that 15-year property which itself qualifies as long-production-period property under §168(k)(2)(B) (a recovery period of at least 10 years, or transportation property, plus the production-period and cost tests) keeps 20% for 2027 on its basis attributable to construction in 2026 or earlier (§168(k)(2)(B)(ii) as in effect before OBBBA); the 5- and 7-year property of a building project cannot be long-production-period property, because that category needs a recovery period of at least 10 years or transportation property. For property acquired after January 19, 2025, placing it in service in January 2027 rather than December 2026 does not change the 100% rate, only the return the deduction lands on, and the acquired date is not the closing date: under IRS Notice 2026-11 it follows the written binding contract rules of Treas. Reg. §1.168(k)-2(b)(5), explained in the January 19, 2025 acquired-date test.
What if a 2026 property's return is filed without a cost segregation study?
For a calendar-year taxpayer that placed a property in service in 2026 and depreciated it on one filed 2026 return without a cost segregation study, two routes are open: Form 3115 filed with the 2027 return, with 2027 as the year of change, when the taxpayer still owned the property at the start of 2027 and meets the other eligibility rules of section 6.01 of Rev. Proc. 2025-23 (the IRS list of automatic changes as we read it on October 26, 2026), or an amended 2026 return filed before the 2027 return is filed.
Under the automatic change procedures of Rev. Proc. 2015-13 and section 6.01 of Rev. Proc. 2025-23, the missed depreciation is claimed on Form 3115 with no amended returns when the property has been depreciated on two or more filed returns, or on one filed return if the taxpayer placed it in service in the tax year immediately before the year of change (the year of the return the Form 3115 is filed with), and the taxpayer still owned the property at the start of the year of change and meets the other eligibility rules.
If the 2026 return has not been filed when the cost segregation study is finished, a property the taxpayer placed in service in 2026 goes on the original 2026 return and needs no Form 3115, which is why the guide to whether a study has to be finished for 2026 depreciation matters before the return is filed. A prior election out of bonus depreciation cannot be undone through this change (section 6.01(1)(c)(vi) of Rev. Proc. 2025-23). The Form 3115 catch-up depreciation guide covers the §481(a) adjustment for property placed in service in earlier years.
What is not known yet about cost segregation in 2027?
The IRS adjusts the §179 dollar limit and its phase-out threshold for inflation each year, and when we read the IRS newsroom on October 26, 2026 it had not published the 2027 inflation-adjusted figures, so this article states no 2027 §179 dollar limit and will be updated when the IRS publishes them. Whether §179 fits a roof, HVAC or other qualified real property next to a cost segregation study is covered in Section 179 vs bonus depreciation for a roof or HVAC.
Under Rev. Proc. 2026-14, the new Opportunity Zones take effect January 1, 2027 for the tracts Treasury designates, and the 2027 Opportunity Zone map is not final until Treasury designates them (by December 28, 2026 at the latest), so a 2027 project's Opportunity Zone status, and with it the Opportunity Zone cost segregation planning, is checked against the final list rather than the nominations.
Is a cost segregation study worth it for property placed in service in 2027?
A cost segregation study is worth it when three conditions hold together: the basis is large enough for the accelerated deductions to outweigh the cost of the study, the deduction is usable this year given the owner's passive-activity position, and the hold is long enough to survive recapture. All three, or the honest answer is no.
For 2027, the first condition now depends on the acquired date as well as the basis: a property acquired on or before January 19, 2025 and placed in service in 2027 gets its acceleration from the shorter 5-, 7- and 15-year recovery periods rather than from bonus depreciation, so the same cost segregation study produces a smaller first-year deduction than it would on property acquired after that date. The line-by-line worth-it analysis shows how the three conditions play out on a real study.
ClickDrag Finance studies are document-driven, human-reviewed and built on the cost classification approach in the IRS Cost Segregation Audit Techniques Guide. The cost segregation qualifier checks whether a 2026 or 2027 property fits a study before the return work begins, and how to compare cost segregation companies sets out what to ask any provider.
Related: Does Depreciation Restart When You Transfer a Rental to an LLC? Cost Segregation for 2026.
Frequently Asked Questions
Does cost segregation still make sense in 2027 for property acquired on or before January 19, 2025?
Cost segregation can still accelerate depreciation in 2027 for qualified property acquired on or before January 19, 2025, but for most of that property placed in service in 2027 the acceleration comes from the shorter 5-, 7- and 15-year recovery periods rather than bonus depreciation, which is 0% for it. A study is worth it only when the basis is large enough for the accelerated deductions to outweigh the cost of the study, the deduction is usable this year given the owner's passive-activity position, and the hold is long enough to survive recapture.
Does property placed in service in January 2027 get depreciation on the 2026 return?
Property placed in service (ready and available for its intended use) in January 2027 is first depreciated on the 2027 return for a calendar-year taxpayer, not on the 2026 return. For a calendar-year taxpayer, a 27.5-year or 39-year shell placed in service on any day in January 2027 earns eleven and a half months of regular depreciation on the 2027 return under the mid-month convention of §168(d)(2).
Is 100% bonus depreciation still available for property placed in service in 2027?
100% bonus depreciation is available for qualified property placed in service in 2027 when it was acquired after January 19, 2025, or, for self-constructed property, when construction began after that date (IRC §168(k) as amended by OBBBA). Qualified property acquired on or before that date and placed in service in 2027 gets 0%, except long-production-period property and certain aircraft, which keep 20% for 2027 under §168(k)(6)(B) as enacted by the Tax Cuts and Jobs Act (long-production-period property only on its basis attributable to construction or production in 2026 or earlier, under §168(k)(2)(B)(ii) as in effect before OBBBA).
Can a cost segregation study be added in 2027 for a property placed in service in 2026?
A cost segregation study can be added in 2027 for a property a calendar-year taxpayer placed in service in 2026: if the 2026 return is not yet filed, the study goes on that original return with no Form 3115, and if one 2026 return was filed without it, the missed depreciation goes on Form 3115 with the 2027 return (when the taxpayer still owned the property at the start of 2027 and meets the other eligibility rules of section 6.01 of Rev. Proc. 2025-23) or on an amended 2026 return filed before the 2027 return is filed.
What is the 2027 section 179 limit for property a cost segregation study identifies?
The 2027 §179 dollar limit and phase-out threshold had not been published by the IRS when we read its newsroom on October 26, 2026, so this article states no 2027 figure. The IRS adjusts both for inflation each year, and §179 applies only to section 179 property under §179(d)(1), which includes qualified real property as defined in §179(e) only at the taxpayer's election, so a tax advisor confirms eligibility for the property a cost segregation study identifies.
