Cost segregation on a short-term rental is one of the most consequential tax strategies in the entire real estate playbook — a well-run study can produce $100,000+ of Year-1 bonus depreciation on a $500,000 STR, offsetting ordinary non-passive income under either the §469(c)(7) 7-day rule or REPS. 100% bonus depreciation is permanent under the One Big Beautiful Bill Act (OBBBA, signed 2025-07-04) for property placed in service on or after 2025-01-19, so the Year-1 math no longer phases down. This guide synthesizes the full DepreciMax cost segregation hub into one place: how the two non-passive-loss pathways work, the pre-purchase vs post-purchase tool sequence, the eight major cost segregation firms, property-type considerations, the CPA workflow, audit defense posture, and the Year-1 math by price band. Each section links to the deep-dive article for the specifics.
TL;DR — the 2026 STR cost segregation landscape
• Two paths to non-passive losses: §469(c)(7) 7-day STR rule, OR real estate professional status (REPS) for long-term rentals.
• Two tools in sequence: pre-purchase screen ($99 DepreciMax) before offer, then post-purchase engineer-signed study ($895–$10,000+) after close.
• Eight cost seg firms serve STRs: KBKG, ETS, Capstan Tax Strategies, CSSI, Madison SPECS, R.E. Cost Seg, FreeCostSeg, Cost Seg EZ. Residential-focused firms are the right call for sub-$1.5M; custom-quote firms for larger / complex.
• 100% bonus depreciation is permanent under OBBBA 2025-07-04 for property placed in service on or after 2025-01-19.
• Year-1 math on a $500K STR: approximately $110K bonus deduction, approximately $41K federal tax savings at 37% marginal.
1. What cost segregation does for a short-term rental
A cost segregation study is an engineering-based analysis that reclassifies components of a property's depreciable basis into shorter-life asset classes. On a short-term rental, the typical reclassification shifts 20–30% of depreciable basis out of the default 27.5-year residential bucket into 5-year personal property (appliances, FF&E, finish flooring, cabinetry, decorative lighting) and 15-year land improvements (pools, hot tubs, pergolas, outdoor kitchens, landscaping, outdoor lighting, retaining walls). Both the 5-year and 15-year buckets are 100% bonus-eligible under IRC §168(k), which means the entire reclassified amount is deductible in the Year 1 the property is placed in service.
The practical outcome for a short-term rental investor: a Year-1 deduction that typically lands in the $60,000 to $400,000+ range depending on purchase price, finish quality, and outdoor amenity density. When paired with the §469(c)(7) 7-day rule or REPS (covered below), those losses are non-passive and offset ordinary income — W-2 wages, business income, or other active earnings.
2. The two paths to non-passive loss treatment
Rental real estate is per-se passive under IRC §469 by default. Two exceptions turn STR cost-seg losses into non-passive deductions that offset ordinary income.
Path A: §469(c)(7) 7-day rule. Reg. §1.469-1T(e)(3)(ii)(A) — if the average rental period is seven days or less, the activity is not treated as a rental activity for passive-loss purposes. Combined with material participation (any of the seven tests in Reg. §1.469-5T), losses are non-passive. This is the standard STR pathway and does not require real estate professional status.
Path B: Real estate professional status (REPS) under IRC §469(c)(7)(B). For long-term rentals or STRs where the 7-day rule doesn't apply, REPS unlocks the same non-passive treatment. Qualification requires more than 750 hours per year in real property trades or businesses AND more than 50% of personal services in those activities. Only one spouse must qualify for married filing jointly. Deep dive: REPS and long-term rentals.
3. Pre-purchase vs. post-purchase: the sequence
Short-term rental cost segregation isn't a single transaction — it's a two-tool sequence. Pre-purchase screens run before the offer; post-purchase engineer-signed studies run after close. The two don't substitute for each other.
Pre-purchase: a $99 property-specific Year-1 bonus depreciation estimate from AI photo analysis + county assessor data. Takes 10 minutes, runs on a shortlist of candidate STRs. Not an IRS-filable deliverable — its job is to inform the acquisition decision.
Post-purchase: an engineer-signed cost segregation study, filed with the return on Form 4562 (or Form 3115 for look-back studies). Takes 2–6 weeks, costs $895–$10,000+ depending on firm and property size. This is the deliverable the IRS examines in an audit.
The economically rational workflow: pre-purchase screen 3–10 candidate STRs for $99 each → close on the one with the strongest Year-1 math → commission the engineer-signed study on that one property for the filing. Deep dive: pre-purchase vs. post-purchase cost segregation.
4. The pre-purchase tool landscape
The pre-purchase category splits into two honest buckets. Property-specific: DepreciMax — $99 per property, analyzes the actual listing photos of the specific unit plus the county assessor land ratio for that address, returns a Year-1 estimate calibrated to a formal study. General-stats: free lead-gen calculators from Cost Seg EZ, Cost Segregation Guys, and FreeCostSeg — return a regional-average deduction from a few typed inputs (sqft, bedrooms, zip) and funnel the user into the vendor's paid study.
The difference matters when comparing candidate properties. Two STRs with identical typed inputs come back with identical numbers from a general-stats calculator, even when their actual finishes, outdoor amenities, and land ratios differ meaningfully. Deep dive: best cost segregation apps for Airbnb hosts.
5. The post-purchase firm landscape
Eight firms serve the short-term rental cost segregation market in 2026, in two tiers:
Published flat-fee (sub-$1.5M residential STRs): Cost Seg EZ Engineer-Reviewed from ~$895, R.E. Cost Seg Rapid Report from $950, FreeCostSeg from $1,200. Mobile-friendly web intake, engineer-signed deliverables, fastest turnaround (days to a week).
Custom-quote (larger / complex / portfolio): KBKG, Engineered Tax Services, Capstan Tax Strategies, CSSI, Madison SPECS. Typically $3,000–$10,000+ with formal audit-defense bench. Fit high-value luxury vacation homes, multifamily, commercial, complex condos requiring HOA common-area allocation, and anywhere the CPA requires a name-brand engineer-signed deliverable.
Deep dive with firm-by-firm "What they offer" / "Customer type" breakdowns: best cost segregation firms for STR investors.
6. Property-type considerations: condos, cabins, luxury
Condos. Among the best STR property types for bonus depreciation — low land ratio (0–10% because the land is HOA-owned), furnished unit interiors heavy on 5-year property, and a pro-rated share of HOA common-area 15-year improvements (pool, hot tub, pergolas, outdoor kitchens). The complexity is in the HOA pro-rata share analysis, not whether to run the study. Deep dive: cost segregation for STR condos.
Cabins and single-family vacation homes. Standard residential cost seg mechanics — higher land ratios than condos (typically 15–30%), but often more outdoor amenity density (fire pits, pergolas, hot tubs, decks) which boosts the 15-year bucket.
Luxury vacation homes ($1.5M+). Custom-quote firm territory. The engineering engagement is more involved (detached casitas, pool complexes, outdoor kitchens, multi-building structures) and the dollar impact is bigger — $350K+ Year-1 deductions are common. Compare property-type Year-1 outcomes side-by-side: cabin vs. condo vs. luxury.
7. The CPA workflow
For CPAs serving STR clients, cost segregation is a four-step workflow spanning acquisition to filing:
- Pre-acquisition screening — DepreciMax screens the client's shortlist, informing the offer decision
- Closing + placed-in-service documentation — depreciation starts when the property is ready and available for rental, typically the first-listing-live date, not necessarily the closing date
- Post-close firm engagement — match firm to property size and client expectation; residential flat-fee for sub-$1.5M, custom-quote for larger
- Filing — Form 4562 for current-year studies, Form 3115 with §481(a) adjustment for look-back studies on prior-year acquisitions (Rev. Proc. 2015-13 automatic consent)
Deep dive with the IRS citations CPAs need for position defense: STR cost segregation for CPAs: a client workflow.
8. Audit defense and documentation posture
Cost segregation studies do not trigger IRS audits. No empirical evidence links a properly executed study to elevated audit risk, and the IRS publishes a Cost Segregation Audit Techniques Guide (ATG) that treats cost seg as standard practice.
Where STR-specific audit risk actually concentrates: material participation substantiation under Reg. §1.469-5T (contemporaneous time logs are the audit standard) and the §469(c)(7) 7-day rule qualification (STR platform booking records establishing the average period). Document both.
Firm-level audit support varies in three tiers: formal written rebuttal services (KBKG's "Rebuttal Support" is a named example; similar scope at CSSI, ETS, Capstan, Madison SPECS), per-hour firm audit support (mid-tier), and documentation-only (entry-tier published-pricing vendors). Ask every firm what their audit-support policy is in writing before signing. Deep dive: cost segregation audit defense for STR investors.
9. Year-1 bonus depreciation math by STR price band
Approximate Year-1 math under current rules (100% bonus permanent under OBBBA), assuming a typical STR with 20% land ratio and a 25% cost seg reclassification rate. Actual figures depend on finish quality, outdoor amenity density, land ratio (lower for condos), and classification judgment on borderline items.
| Purchase price | Depreciable basis | 5-yr + 15-yr reclass (25%) | Year-1 bonus deduction | Plus first-year 39-yr MACRS | Total Year-1 write-off | Federal tax savings at 37% |
|---|---|---|---|---|---|---|
| $300,000 | $240,000 | $60,000 | $60,000 | ~$6,000 | ~$66,000 | ~$24,400 |
| $500,000 | $400,000 | $100,000 | $100,000 | ~$10,000 | ~$110,000 | ~$40,700 |
| $750,000 | $600,000 | $150,000 | $150,000 | ~$14,000 | ~$164,000 | ~$60,700 |
| $1,500,000+ (luxury, 30% reclass) | $1,200,000 | $360,000 | $360,000 | ~$28,000 | ~$388,000 | ~$143,600 |
Illustrative only. State tax savings on top of federal. Actual results depend on cost segregation firm's component classification, land-ratio sourcing, outdoor amenity density, finish quality, and whether the taxpayer qualifies under the §469(c)(7) 7-day rule or REPS to treat the losses as non-passive. Nothing here is tax advice; confirm with a licensed CPA.
10. Decision tree: your situation → where to start
- Haven't closed yet, evaluating candidate STRs? Start with a $99 DepreciMax pre-purchase screen on each candidate. The screen tells you the Year-1 math before you commit the capital.
- Just closed on a sub-$1.5M residential STR? Engage a flat-fee residential-focused firm: Cost Seg EZ Engineer-Reviewed, R.E. Cost Seg Rapid Report, or FreeCostSeg. See the firms roundup.
- Just closed on a $1.5M+ or complex STR? Custom-quote firm — KBKG, Engineered Tax Services, Capstan Tax Strategies, CSSI, or Madison SPECS.
- Closed years ago and never ran cost seg? Look-back study via Form 3115 §481(a) adjustment catches up all missed depreciation on the current year's return. Any of the firms above handle this.
- You're a CPA or EA with multiple STR clients? See the CPA client workflow and consider DepreciMax Pro ($249/mo, 3-month minimum) for cross-client screens.
- You're a long-term rental investor who qualifies as a real estate professional (REPS)? See REPS and long-term rentals. DepreciMax works for LTR screening too.
Start with a pre-purchase screen — $99
Pre-purchase screen for your next STR — $99
Paste any US short-term rental address. Get a property-specific Year-1 bonus depreciation estimate in under 10 minutes.
Run a Property Report — $99 →Frequently Asked Questions
What is cost segregation for a short-term rental?
Cost segregation is an engineering-based study that reclassifies components of a property's depreciable basis into 5-year personal property (appliances, FF&E, finish flooring), 15-year land improvements (pools, hot tubs, pergolas, outdoor kitchens, landscaping), and 39-year or 27.5-year structural property. The 5-year and 15-year buckets are 100% bonus-eligible under IRC §168(k) in the first year, producing outsized Year-1 deductions for short-term rental investors.
How much Year-1 bonus depreciation can an STR produce?
A $500,000 short-term rental with a 20% land ratio typically produces about $110,000 of Year-1 bonus depreciation under current IRC §168(k) rules — roughly $41,000 in Year-1 federal tax savings at a 37% marginal rate. A $300K STR lands around $66K Year-1 write-off; a $1.5M+ luxury STR with heavy outdoor amenities can hit $380K+. Exact numbers depend on land ratio, finish quality, and outdoor amenity density.
Do I need to be a real estate professional to benefit from cost segregation on an STR?
No, if you qualify under the §469(c)(7) seven-day STR rule (Reg. §1.469-1T(e)(3)(ii)(A)): an average rental period of 7 days or less makes the activity non-rental for passive-loss purposes, so cost-seg-driven losses offset non-passive income when you materially participate. Real estate professional status (REPS) under §469(c)(7)(B) is the separate pathway for long-term rental investors.
What's the difference between pre-purchase and post-purchase cost segregation?
Pre-purchase cost segregation screens a property before you write an offer — tools like DepreciMax run a $99 property-specific Year-1 estimate from listing photos + county assessor data. Post-purchase cost segregation is the engineer-signed study you file with your return after close — $895 to $10,000+ depending on firm and property size. The two stack: pre-purchase on your shortlist, post-purchase on the one you actually buy.
Who are the best cost segregation firms for short-term rentals?
Eight firms serve the STR market: KBKG, Engineered Tax Services, Capstan Tax Strategies, CSSI, Madison SPECS, R.E. Cost Seg, FreeCostSeg, and Cost Seg EZ. For sub-$1.5M residential STRs, published flat-fee vendors (Cost Seg EZ ~$895, R.E. Cost Seg $950+, FreeCostSeg $1,200+) typically fit best. For larger or complex properties, custom-quote firms (KBKG, ETS, Capstan, CSSI, Madison SPECS) carry the audit-defense bench.
Does cost segregation trigger an IRS audit?
No empirical evidence links a properly executed cost segregation study to elevated audit risk. The IRS publishes a Cost Segregation Audit Techniques Guide, and studies that meet its 13 principal elements are standard practice. STR-specific audit risk concentrates on material participation substantiation and the 7-day rule qualification — not on the cost seg study itself.
Can I do cost segregation on a condo?
Yes — and condos are among the best STR property types for cost segregation. Three factors stack in a condo's favor: very low land ratio (0–10%, land is HOA-owned), heavy 5-year unit interior (furnished STRs), and pro-rated share of HOA common-area 15-year land improvements (pool, hot tub, pergolas, outdoor kitchen). The complexity is in the HOA pro-rata share analysis, not whether to run the study.
What if I already closed on a short-term rental without doing cost segregation?
You can still do a look-back cost segregation study via Form 3115 §481(a) change-in-accounting-method filing. This catches up all missed depreciation from prior years in a single current-year adjustment, with no prior-year amendments required. Rev. Proc. 2015-13 provides automatic consent. All major cost segregation firms handle look-back studies.
Does cost segregation work on long-term rentals?
Yes, with REPS. For long-term rental investors who qualify as real estate professionals under IRC §469(c)(7)(B) (more than 750 hours in real property trades or businesses AND more than 50% of personal services in those activities, both in the same year), cost segregation produces the same Year-1 economics as it does for an STR under the 7-day rule.
Where should I start if I'm considering cost segregation on an STR?
Three starting points depending on where you are. Pre-purchase (haven't closed yet): run a $99 DepreciMax pre-purchase screen to see the Year-1 math before you write the offer. Post-purchase (just closed): engage one of the cost segregation firms — residential-focused flat-fee for sub-$1.5M, custom-quote for larger. Already owned for years without cost seg: a Form 3115 §481(a) look-back study catches up the missed depreciation.
Sources & further reading
Deep-dive articles in this hub:
- Best Cost Segregation Firms for STR Investors (2026)
- Best Cost Segregation Apps for Airbnb Hosts (2026)
- Cost Segregation for Short-Term Rental Condos (2026)
- Pre-Purchase vs. Post-Purchase Cost Segregation
- STR Cost Segregation for CPAs: A Client Workflow
- Cost Segregation Audit Defense for STR Investors
- REPS and Long-Term Rentals: Cost Segregation Still Pays
- Best Cost Segregation Software for Short-Term Rentals (2026)
- Cabin vs. Condo vs. Luxury: Which Property Type Has the Best Bonus Depreciation?
IRS and primary tax authority:
- IRC §168(k) — Bonus depreciation (100% permanent under OBBBA): 26 U.S.C. §168
- IRC §469(c)(7)(B) — Real estate professional: 26 U.S.C. §469
- Treasury Reg. §1.469-1T(e)(3)(ii)(A) — STR 7-day exception: 26 CFR §1.469-1T
- IRS Notice 2026-11 — OBBBA bonus depreciation operational guidance: irs.gov/pub/irs-drop/n-26-11.pdf
- IRS Publication 946 — How to Depreciate Property: irs.gov/publications/p946
- IRS Cost Segregation Audit Techniques Guide: irs.gov cost segregation ATG
- IRS Form 3115 — Application for Change in Accounting Method: irs.gov/forms-pubs/about-form-3115
- Rev. Proc. 2015-13 — Automatic consent for change in accounting method: irs.gov Rev. Proc. 2015-13
Disclaimer. DepreciMax is a technology company that publishes bonus depreciation screening tools and educational content. We are not CPAs, Enrolled Agents, tax attorneys, licensed engineers, or an authorized representative of any taxpayer before the IRS. Nothing in this guide is tax advice, legal advice, or a substitute for professional counsel. Firm names, pricing, and feature descriptions were current as of the publish date and were sourced from each vendor's public website. Always confirm current terms directly with each firm and your licensed tax professional before filing a position.