Cost segregation is the most over-marketed tax strategy in the STR space. Every operator who’s heard about it once has been pitched a $5,000 engineering study. Whether it pays for itself comes down to one number — the property’s depreciable basis — and most $200K STRs don’t clear it. Here’s the math you can run on a napkin before you sit through a sales call.
What cost segregation actually does
A residential rental gets depreciated over 27.5 years straight-line. A cost-segregation study reclassifies a chunk of the property — fixtures, flooring, cabinetry, landscaping, driveways, certain plumbing and electrical components — into 5-, 7-, and 15-year property buckets. Those shorter-life buckets become eligible for bonus depreciation, which means a big slug of deductions in year one instead of spread across three decades.
It does not create new deductions. It pulls them forward. The total amount you depreciate over the life of the asset is the same — you just take more of it earlier.
The break-even, in one paragraph
A typical cost-seg study runs $3,000–$8,000 for a single-family STR under $1M. The study usually reclassifies 20–30% of the depreciable basis into shorter-life buckets. With bonus depreciation at the current schedule (phasing down — verify the rate for your placed-in-service year), you accelerate the deduction on that 20–30% into year one.
Quick numbers on a $400,000 property (excluding land):
- Land: $100,000 (non-depreciable, never)
- Building: $300,000
- Typical reclass: 25% = $75,000 to short-life property
- Bonus depreciation (assume 60% this year): $45,000 of that accelerated into year one
- At a 32% marginal federal rate: ~$14,400 of tax saved in year one
- Study cost: $5,000
That’s a clean win at $400K. Run the same math at $200K — building basis $150K, reclass $37,500, bonus $22,500, tax saved $7,200 — and the $5,000 study eats more than half the year-one benefit, with present-value erosion on the slower turnaround.
The number that decides it
Roughly: building basis under $250K, the math gets thin. Above $350K, it almost always pencils. In between, it depends on your marginal rate, the bonus percentage for your placed-in-service year, and whether you can actually use the loss against your other income.
That last clause is the one operators forget.
Why the loss has to land somewhere usable
Accelerated depreciation creates a loss on the STR. Schedule E losses are passive by default — they can’t offset W-2 or active business income unless you’re a real estate professional or you’ve structured the STR to fall outside §469 entirely (the so-called “STR loophole” covered in Schedule E vs Schedule C).
If the loss just gets suspended on Form 8582 and carried forward, the present-value math on cost seg gets ugly. You’re paying $5K today for a deduction you can’t use until you sell. Don’t pay for the study until you know where the loss lands.
What a study can and can’t reclassify
| Component | Typical bucket |
|---|---|
| Land improvements (driveway, landscaping, fence) | 15-year |
| Carpeting, vinyl flooring | 5-year |
| Cabinetry, countertops (sometimes) | 5-year |
| Removable appliances | 5-year |
| Specialty electrical (kitchen, lighting circuits) | 5- or 7-year |
| Structural shell, roof, framing, foundation | Stays at 27.5-year |
| Land itself | Never depreciated |
A “DIY cost seg” using a residential rental cost-seg calculator is not the same as an engineering-based study. The IRS has been clear since the 2004 audit techniques guide that opinion-based segregations get challenged. If you’re going to do it, get the engineering study and keep the report — it’s the audit defense.
Recapture is real
When you sell, the depreciation you took on short-life property gets recaptured at ordinary rates (up to 37%), not the 25% real estate rate on the 27.5-year portion. If you’re planning to hold and 1031 into the next property, recapture defers along with the rest. If you’re planning to sell outright, the year-of-sale tax bill is bigger than a straight-line depreciation operator would see.
This isn’t a reason to skip cost seg — the time value of money usually still wins — but it is a reason to model the sale, not just the acquisition.
The honest decision tree
- Depreciable basis under $250K? Probably skip the engineered study. Take straight-line depreciation, move on.
- Basis $250K–$400K? Get a free analysis from a cost-seg firm — most will run the model at no cost and only charge if you proceed. Run the present-value math against your marginal rate.
- Basis above $400K and an STR loophole loss that lands usable? Do the study. The numbers almost always work.
- Basis above $400K but you’re stuck with passive loss limitations and no exit in sight? Model the carryforward and decide whether you’d rather have the deduction now (suspended) or later (against gain at sale).
Where the workbook helps
The Cost Segregation DIY Workbook — $47 — is the IRS-acceptable self-performed method for properties under $1M: you walk the property, allocate each component into the 5/7/15-year buckets, overlay the current-year bonus percentage, and produce the year-one comparison and asset breakdown your CPA needs to file — the same output a $3,000–$8,000 study delivers, for the properties where the engineered study doesn’t pencil. Once the schedule exists, the Schedule E Workbook ($47) carries those accelerated-depreciation schedules forward year over year, keeps the 5/7/15-year buckets separate from the 27.5-year shell, and flags recapture exposure when you mark a property as “planning to sell” so the surprise doesn’t arrive on your final return.
Not sold on a workbook yet? The free 47 STR deductions checklist shows where depreciation sits among the deductions hosts most often miss — a low-stakes first step before you commit to a study or a workbook.
This is general information, not tax advice. Cost seg interacts with §469, bonus depreciation phase-downs, and your specific marginal rate in ways this post doesn’t model. Get the engineering study from a licensed firm and your CPA’s sign-off before you take the deduction.