The Problem With the Standard Depreciation Schedule

When you purchase an STR, the IRS default is to treat the entire building as a single asset and depreciate it over 27.5 years on a straight-line basis. On a $500,000 property with $400,000 allocated to the depreciable building:

Standard 27.5-Year Depreciation:

$400,000 ÷ 27.5 years = $14,545 per year

$14,545 per year is a meaningful deduction. But it barely scratches what’s actually available — because a building isn’t one uniform 27.5-year asset. It’s a collection of hundreds of individual components, each with its own useful life. The flooring. The cabinetry. The electrical fixtures. The appliances. The landscaping. The driveway. Each of those components depreciates faster than the building structure itself. That identification is what a cost segregation study does.

The 27.5 vs. 39-Year Depreciation Debate: The 30-Day Transient Trap

Before modeling your cost segregation benefit, there is a threshold question your CPA needs to answer: is your STR eligible for the 27.5-year residential depreciation schedule, or does the nature of short-term rental activity force it onto the 39-year commercial schedule?

The statute: Under IRC §168(e)(2)(A), a property qualifies for 27.5-year residential depreciation only if 80% or more of its gross rental income comes from dwelling units. The code explicitly states that a unit in a hotel, motel, inn, or other establishment more than one-half of whose units are used on a transient basis does not qualify. The IRS generally defines “transient” as an average stay of 30 days or fewer.

27.5-Year Residential Baseline:

$400,000 ÷ 27.5 years = $14,545 per year

39-Year Nonresidential Baseline:

$400,000 ÷ 39 years  = $10,256 per year

Difference: $4,289 less per year in straight-line deductions

under the 39-year schedule before cost segregation begins.

The practitioner divide: The aggressive position holds that if a property’s average rental period is 30 days or fewer, the transient-use exclusion applies and the property must be classified as nonresidential. The conservative position argues that a single-family home is not an “establishment” in the sense the statute intends — it’s a house, not a hotel — and 27.5-year treatment is defensible. The IRS has not issued a definitive ruling resolving the question for single-family STRs.

CPA Tip — Conditional QIP Access: If your CPA determines your property warrants 39-year nonresidential classification, there is a significant silver lining. Under IRC §168(e)(6), Qualified Improvement Property (QIP) — interior improvements to nonresidential buildings made after the building is placed in service — carries a 15-year life and qualifies for 100% bonus depreciation under the OBBBA. A major post-purchase kitchen renovation or interior upgrade could be fully expensed in the year it’s made. This benefit is only available under the 39-year classification.

📘 Included in the STR Financial Bible: Use the 02_STR_Deal_Analysis_Spreadsheet.xlsx to model both scenarios — 27.5-year versus 39-year baseline — against your projected cost segregation reclassification before engaging a cost segregation firm.

What Cost Segregation Actually Does

A cost segregation study is an engineering-based analysis that identifies which components qualify for 5-year or 15-year depreciation instead of 27.5 years:

• Personal property (5–7 year MACRS): Carpeting, certain fixtures, appliances, specialized electrical components, cabinetry, and other interior components considered personal property rather than structural.
• Land improvements (15-year MACRS): Driveways, parking areas, landscaping, fencing, outdoor lighting, walkways, patios, and pools.

Everything that doesn’t get reclassified stays on the 27.5-year building schedule. The reclassification alone accelerates your deductions — but the real multiplier is bonus depreciation.

Bonus Depreciation: The Accelerant

Under the OBBBA, qualifying personal property and land improvements placed in service after January 19, 2025 are eligible for 100% bonus depreciation in year one. Every dollar reclassified to 5-year or 15-year property is fully deductible in the year it’s placed in service.

Full Math — $500,000 STR with Cost Segregation at 100% Bonus:

Property purchase price:         $500,000

Land allocation (20%):           $100,000

Depreciable building basis:      $400,000

Cost segregation reclassification:

  5-year personal property:       $90,000 → 100% bonus = $90,000 year-one

  15-year land improvements:      $35,000 → 100% bonus = $35,000 year-one

  27.5-year building remainder:  $275,000 → $275,000 ÷ 27.5 = $10,000 year-one

Total year-one WITH cost segregation:    $135,000

Total year-one WITHOUT cost segregation:  $14,545

Additional year-one deduction:           $120,455

At 32% combined bracket:

  Tax savings: $120,455 × 32% = $38,545

  Less study cost:               ($4,500)

  Net year-one benefit:          $34,045

The Look-Back Study: Claiming Missed Depreciation Without Amending Returns

If you purchased your STR one, two, or three years ago without doing a cost segregation study, you have been depreciating the entire building on the 27.5-year schedule. A look-back study quantifies the depreciation you should have taken, and the Form 3115 process allows you to claim all of that missed depreciation in the current tax year as a single catch-up deduction — without filing amended returns.

This is a well-established IRS procedure under Revenue Procedure 2015-13 and the automatic change in accounting method rules.

Look-Back Example:

Operator purchased STR in 2022 for $500,000

Has been using standard 27.5-year depreciation

A 2024 look-back study identifies:

  → $90,000 of 5-year property (should have been 100% expensed in 2022)

  → $35,000 of 15-year property (should have been 100% expensed in 2022)

Catch-up calculation:

  Depreciation that should have been taken (2022–2023):

    5-year:  $90,000

    15-year: $35,000

    27.5-yr: $10,000 (two years at $5,000/yr on $275,000 remainder)

    Total:  $135,000

  Depreciation actually taken (2022–2023):

    $14,545 × 2 years = $29,090

  Section 481(a) catch-up adjustment: $135,000 − $29,090 = $105,910

→ This $105,910 deduction flows into the 2024 tax return

→ No amended returns for 2022 or 2023 required

→ At 32% bracket: ~$33,900 in tax savings in one year

How Form 3115 Works: The Mechanics

Form 3115 is the IRS form for requesting a change in accounting method. You are changing from the incorrect method (27.5-year straight-line on all components) to the correct method (MACRS with appropriate asset class lives and bonus depreciation elections).

Step 1: The Cost Segregation Study

A qualified cost segregation firm — typically employing engineers following the IRS Cost Segregation Audit Techniques Guide — conducts the engineering analysis and produces a study report itemizing each reclassified component, its cost basis, assigned asset life, and applicable depreciation method.

Step 2: Recalculate Prior-Year Depreciation

Your CPA recalculates what your depreciation would have been in each prior year using the correct asset classifications. The difference between what you should have taken and what you actually took is computed on an asset-by-asset basis.

Step 3: Calculate the Section 481(a) Adjustment

The cumulative shortfall becomes the Section 481(a) adjustment. A negative adjustment (under-depreciation) is deductible in full in the year of filing. A positive adjustment (over-depreciation) must be spread over four years. The IRS deliberately designed this asymmetry to incentivize taxpayers to self-correct depreciation errors.

Section 481(a) Adjustment Formula:

  Depreciation correctly computed under new method (all prior years)

− Depreciation actually taken under prior method (all prior years)

= Section 481(a) adjustment

  (negative = full deduction in year of change)

  (positive = spread over 4 years)

Step 4: File Form 3115 With the Current-Year Return

Form 3115 is attached to your Form 1040 for the year of change. A signed duplicate copy is also filed separately with the IRS PIN Team:

Internal Revenue Service

201 West Rivercenter Blvd, PIN Team Mail Stop 97

Covington, KY 41011-1424

Miss the duplicate filing and the change is technically incomplete. The Section 481(a) adjustment flows through to Schedule E as additional depreciation — not as a separate line item.

Which Automatic Change Number Applies

Situation	Applicable Change
Reclassifying property to correct MACRS asset class	DCN 7 — Change in depreciation method
Late bonus depreciation election	DCN 7 or separate late-election procedure
Changing from incorrect to correct depreciation period	DCN 7
Changing from incorrect to correct depreciation method	DCN 7

The Depreciation Recapture Trade-Off

Every dollar of accelerated depreciation reduces your adjusted basis. When you sell, a lower basis means a larger taxable gain.

Section 1245 recapture applies to 5-year and 7-year personal property — taxed as ordinary income at your marginal rate (up to 37%).

Section 1250 recapture applies to 15-year land improvements — capped at a maximum rate of 25%, not ordinary income rates.

Recapture Example at Sale:

  STR purchased for $500,000 in 2022

  Accelerated deductions taken: $125,000

  Standard 27.5-yr depreciation 2022–2027: ~$60,000

  Adjusted basis at 2027 sale: $500,000 − $125,000 − $60,000 = $315,000

  Sale price: $650,000

  Total gain: $335,000

  Section 1245 recapture (personal property): $90,000 at ordinary rates (~32%)

  Section 1250 recapture (building):          $60,000 at max 25%

  Remaining capital gain:                    $185,000 at 15–20%

The strategy is most powerful for operators planning a hold of 5+ years, or those intending to execute a 1031 exchange at sale — which defers both the capital gain and the recapture and resets the cycle.

📘 Included in the STR Financial Bible: Use the 02_STR_Deal_Analysis_Spreadsheet.xlsx to model your exit recapture drag against the time-value benefit of the year-one deduction. Run at least three hold-period scenarios — 3 years, 5 years, and 7+ years.

Who Should Actually Do This

Quick Qualification Screen:

  Purchase price ≥ $300,000?                    → Proceed

  W-2 or other income to absorb the deduction?  → Proceed

  Qualified for non-passive STR treatment?       → Proceed

  Planned hold ≥ 3 years?                        → Proceed

  All four: Schedule the study conversation now.

Condition 1 — Property value above $300,000. On a $200,000 property, the reclassifiable component pool is smaller and the math often doesn’t pencil. The strategy gets significantly more powerful above $400,000.

Condition 2 — Sufficient income to absorb the deductions. The strategy is most powerful for operators with significant W-2 income who have qualified for non-passive STR treatment through the average rental period test and material participation.

Condition 3 — A hold period of at least 3–5 years. Model the recapture picture with your CPA before pulling the trigger.

What to Bring to Your CPA

• Your original closing disclosure (HUD-1 or CD) — needed to establish your depreciable basis correctly
• Your current depreciation schedule — pull Schedule E from your most recent filed return
• Your property tax assessment breakdown — the land-to-building ratio establishes the land allocation
• Any capital improvements made since purchase — new decks, pools, kitchen renovations may have segregatable components

Questions to ask your CPA directly: Does my property qualify? Is a look-back study available? What is the estimated Section 481(a) catch-up adjustment? What is the projected net benefit? How does the recapture picture look at 3 years vs. 7 years?

Frequently Asked Questions

Does cost segregation require amending my prior-year returns?

No. The Form 3115 captures the entire cumulative shortfall as a Section 481(a) adjustment on your current-year return. You file one form with your current return — not a stack of amended returns. This is the correct procedure under Rev. Proc. 2015-13 (as updated by Rev. Proc. 2023-24).

How far back can a look-back study go?

There is no hard cutoff — the Section 481(a) adjustment captures all years from the placed-in-service date through the year of filing. Practically, properties purchased in 2020–2023 represent the strongest look-back window given the bonus depreciation rates in effect during those years.

Does the cost segregation study need to be done by an engineer?

The IRS Cost Segregation Audit Techniques Guide explicitly states that a quality study should involve professionals with engineering or construction knowledge. Studies applying generic reclassification percentages without property-specific analysis carry higher audit risk. For a residential STR in the $300,000–$700,000 range, a qualified study takes 2–4 weeks and costs $3,000–$6,000.

Can I do cost segregation if my STR is in an LLC?

Yes. The depreciation treatment passes through to the owner’s individual return regardless of whether the property is held in a single-member LLC (disregarded entity) or a partnership. Your CPA handles the filing entity determination.

Will cost segregation trigger an audit?

Cost segregation is a mainstream strategy supported by IRS guidance. What attracts scrutiny is a study with no engineering support, incorrect Form 3115 preparation, or deductions inconsistent with the property’s characteristics. Use a reputable firm and a CPA who handles cost segregation regularly.

What happens to unused losses if my STR doesn’t qualify for non-passive treatment?

The accelerated depreciation still creates passive losses — suspended and carried forward. They release when you generate passive income from this or other passive activities, or in full when you sell. The strategy still makes long-term sense, but the near-term cash benefit is deferred.

Matt Nunn, CPA has been in public accounting since 2006. Builder’s Finance Co publishes financial education content for short-term rental operators. All tax and accounting claims in this article reflect the author’s professional interpretation and should not be relied upon as tax advice for your specific situation. Consult your CPA before making tax elections or strategic decisions. Pursuant to IRS Circular 230, any tax advice contained in this communication was not intended or written to be used, and cannot be used, for the purpose of avoiding tax-related penalties.