The default answer was 27.5 years. Buy a residential rental property and the default treatment is one assumption: the whole thing is a single asset, written off over 27.5 years. For a $534,801 residential rental property in Boston, that path would have handed the owner's deductions back in thin, even slices, about $19,000 a year, for decades.
There is nothing improper about the long schedule. It is simply the assumption you inherit if nobody counts what is in the building. The code treats a property as a stack of assets with different recovery periods, and only the shell and its structural components belong on the long one.
What an engineered study looks for in a residential rental property
A rental house or small residential building is a 27.5-year asset by default, but its carpet and removable flooring, appliances, dedicated systems, driveway, fencing and qualifying landscaping are examined separately. The building runs 1,099 SF.
The Cost Seg America team analyzed this property component by component, across the whole property, under the first two approaches the IRS Audit Techniques Guide describes (Approaches 1 and 2): detailed engineering from actual cost records, and engineering with documented estimates reconciled to what the owner paid. Not a questionnaire. Not an estimated study that runs the address through a template and returns an average. An engineering analysis of the structure, the site work and the systems that an estimate never separates, documented so a CPA can import it and an examiner can trace every number to its source.
Examined as personal property, bonus eligible: Carpet and vinyl flooring, appliances, dedicated electrical for appliances and equipment, low-voltage, data and security wiring, specialty lighting, window treatments and similar removable items.
Examined as land improvements, bonus eligible: Driveway and walkways, fencing and gates, qualifying landscaping and irrigation, exterior lighting, patios and decks, retaining walls.
Kept with the building, 27.5 years: Shell, framing and foundation, roof, base HVAC, plumbing and electrical distribution, windows and doors.
Which specific items land in which category is what the study determines, from the building and the records. Counting every component finds what is actually there, which averages miss in both directions.
The result
$205,334, 38% of the property's basis, was documented as shorter-life property and moved off the long schedule into faster federal depreciation. That is not an estimate or a projection. It is what the engineered analysis documented on this building, to the elements of a quality study the IRS describes for its own examiners in the Cost Segregation Audit Techniques Guide, Publication 5653.
Nothing was created here. The $205K was always the owner's to deduct. What changed is timing, and timing is the whole point: a deduction taken now is cash now, and a deduction thirty years out has been thinned by inflation before it lands.
Under the One Big Beautiful Bill Act, signed July 4, 2025, 100% bonus depreciation applies to qualifying property acquired and placed in service after January 19, 2025, automatically unless the taxpayer elects out, by property class, on the return. The short-life property an engineered study finds is exactly what qualifies. For property placed in service earlier, the bonus rate of that year applies, and a look-back study claims the catch-up in the current year.
What accelerating $205K is worth
Illustrative first-year federal income tax savings on the reclassified components, if 100% bonus depreciation applied and at a 37% federal rate: $75,974. Without a study, a full year's deduction on this basis would have been about $19,000, worth about $7,200 of tax at the same rate; the first year is prorated by the month placed in service. Illustrative only, not a promise of results: the figure is computed from this study's real reclassified amount using the assumptions shown, federal only, and your benefit depends on your tax situation, the year the property was placed in service, and the passive activity rules. Your CPA determines what applies to you.
What owners ask about a result like this
Can this still work on a property I have owned for a while? Yes. The IRS allows a look-back study on a building you already own. For a building already depreciated on two or more filed returns, the mechanism is a Form 3115 change in accounting method filed with your normal return, and the depreciation you should already have claimed comes back in a single year as a Section 481(a) catch-up, at the bonus rate of the year the property was placed in service. No amended returns. Cost Seg America prepares the computation, and the Form 3115 itself for a separate fee.
Does a result this size draw attention? The IRS does not publish its selection criteria, so no honest firm says a study will or will not be examined. What we can say is how a study holds up when it is: every Cost Seg America study is built under Approaches 1 and 2, signed by credentialed professionals, and defended by Cost Seg America for as long as you own the building, with no time limit, no hour cap and no additional fee. Across 125+ IRS examinations, zero losses and not one dollar returned.
And when the building sells? Depreciation always factors into a sale, with or without cost segregation, and your CPA plans for it in advance. For most holders the value of deductions now outweighs the treatment at exit, and a 1031 exchange can defer it. It is a planning conversation, not a reason to hold back.
Should I expect the same 38% on my building? Not automatically. An engineered study typically reclassifies 20% to 35% of depreciable basis, and the share on any one building reflects how it was built and fitted and how much surrounds it outside. A free proposal estimates yours, in writing, before any commitment.
Figures are from the completed study on this property. The owner's name and identifying details are withheld. Educational content, not tax advice; your CPA applies the results to your return.
An engineered cost segregation study on a residential rental property in Boston, MA reclassified $205,334 (38%) of a $534,801 basis into faster federal depreciation. Engineered, not estimated, by the Cost Seg America team.
Property details
1,099 SF
Building Size