The main cost segregation firms serving short-term rental investors in 2026 are KBKG, Engineered Tax Services, Capstan Tax Strategies, CSSI, Madison SPECS, R.E. Cost Seg, FreeCostSeg, and Cost Seg EZ. All eight are post-purchase tools: they produce the engineer-signed cost segregation study you file with your return after you've already closed on the property. DepreciMax is a pre-purchase tool. It runs before you write the offer and returns a property-specific Year-1 bonus depreciation estimate from AI analysis of the actual listing photos — so the number is calibrated to the specific property, not pulled from regional averages the way free pre-purchase calculators are. The pre- and post-purchase tools stack in sequence; this article covers both lanes and shows how to pick the right one for your moment in the deal.
TL;DR — pre-purchase vs post-purchase cost seg tools for STR investors (2026)
• Pre-purchase, property-specific: DepreciMax — $99 per property. AI analysis of the actual listing photos. Runs before you write the offer.
• Pre-purchase, general-stats: Free calculators from Cost Seg EZ, Cost Segregation Guys, FreeCostSeg. Return a regional-average estimate from a few typed inputs (sqft, bedrooms, zip). No property-specific analysis. Lead-gen for the paid study.
• Post-purchase, published flat-fee (single-family STR): Cost Seg EZ (~$895 Engineer-Reviewed), R.E. Cost Seg ($950 Rapid Report), FreeCostSeg ($1,200+).
• Post-purchase, custom-quote: KBKG, Engineered Tax Services, Capstan Tax Strategies, CSSI, Madison SPECS.
• Post-purchase + R&D credit + 179D + 45L bundled: Engineered Tax Services, KBKG, Capstan Tax Strategies.
• Post-purchase at portfolio / institutional scale: Madison SPECS, KBKG.
How we evaluated the firms
For each firm below we reviewed public materials (home page, cost segregation service page, pricing page where published, “about” copy) and categorized by headquarters, service lines, typical property-size fit, and whether pricing is published. Firms are listed in no particular order.
Disclosure. DepreciMax is published by the operator of this site. It is a pre-offer estimator, not a cost segregation study, and does not compete with the eight firms below on the same job. Any investor who buys a property should still have a formal cost segregation study produced by one of the firms in this roundup (or an equivalent) before filing.
What to look at when picking a firm
Short-term rentals are residential property under IRS classification (27.5-year recovery), but they generate commercial-grade Year-1 deductions when the IRC §469(c)(7) seven-day average-stay rule applies and the owner materially participates. Firms vary on four variables that determine fit:
1. Property-size threshold. KBKG's cost segregation page states the firm's offering is built for properties above $1.5 million depreciable basis. Firms with explicit sub-$1.5M residential tiers include R.E. Cost Seg, FreeCostSeg, and Cost Seg EZ.
2. Residential vs. commercial focus. ETS, Capstan, Madison SPECS, and CSSI handle residential work; the primary engagement shape at each is multifamily, commercial, or portfolio. R.E. Cost Seg and FreeCostSeg explicitly market to Airbnb and short-term rental owners on their home pages.
3. Published vs. custom-quote pricing. Three firms publish per-study pricing: R.E. Cost Seg ($950+ Rapid Report, $2,320+ Fully Engineered), FreeCostSeg ($1,200–$5,000 flat), Cost Seg EZ (~$895 Engineer-Reviewed, from ~$2,500 Fully Engineered). The other five — KBKG, ETS, Capstan, CSSI, Madison SPECS — are custom-quote only.
4. Audit-support posture. Engineer-signed studies include some level of post-filing audit support. The scope varies — from responding to IRS questions on request to formal written rebuttal services. The specifics are often not on the public page; ask each firm before signing.
The 8 best cost segregation firms for STR investors in 2026
| Firm | Customer type | Property size | Pricing | What they offer |
|---|---|---|---|---|
| DepreciMax | Pre-purchase — buyer screening a property before writing the offer | Any STR | $99/property or $249/mo Pro (3-month min) | Property-specific Year-1 bonus depreciation estimate from AI analysis of the actual listing photos. Not a cost segregation study. |
| KBKG | Post-purchase — post-close owner working through a CPA | $1.5M+ (per KBKG's own threshold copy) | Custom quote (not published) | Engineer-signed cost seg studies. Also R&D credit, 179D, 45L, TPR consulting. Pasadena CA, 1999, 8 US offices. |
| Engineered Tax Services (ETS) | Post-purchase — owners pursuing multiple engineering tax incentives in one engagement | Mid-market to enterprise | Custom quote (not published) | Engineer-signed cost seg studies, R&D credit, 179D, 45L, grants. West Palm Beach FL. |
| Capstan Tax Strategies | Post-purchase — multifamily and commercial owners with tangible-property-regs work | Commercial / larger multifamily | Custom quote (not published) | Engineer-signed cost seg studies, 179D, 45L, tangible property analysis. Philadelphia area. |
| CSSI (Cost Segregation Services, Inc.) | Post-purchase — CPAs placing studies via a referral network | SFR through commercial | Custom quote (not published) | Engineer-signed cost seg studies with CPA-channel distribution; look-back / §481(a) support. Louisiana. Publishes 45,000+ studies completed. |
| Madison SPECS | Post-purchase — institutional and larger-portfolio owners | Portfolio / commercial / larger multifamily | Custom quote (not published) | Engineer-signed cost seg studies at portfolio scale. Part of Madison Commercial Real Estate Services. |
| R.E. Cost Seg | Post-purchase — residential owners wanting published flat-fee pricing | SFR, STR, small multifamily | $950+ Rapid Report; $2,320+ Fully Engineered residential; $2,730+ commercial | Two-tier engineer-signed studies (Rapid Report + Fully Engineered). Houston TX. Explicit Airbnb / STR coverage. |
| FreeCostSeg (Modern CFO) | Post-purchase — residential owners wanting the lowest-cost engineer-signed study | SFR, STR, duplex – 4-plex | $1,200–$5,000 flat (most residential $1,200–$1,600) | Flat-fee engineer-signed studies (ASCSP-member sign-off), AI-assisted workflow, instant online benefit estimator. Founded 2024. |
| Cost Seg EZ | Post-purchase — residential owners choosing between DIY, engineer-reviewed, or fully engineered output | Residential under $1M | ~$895 Engineer-Reviewed; from ~$2,500 Fully Engineered | Three-tier product (DIY, Engineer-Reviewed, Fully Engineered). Princeton NJ. STR listed as a supported property type. |
On pricing: Only R.E. Cost Seg, FreeCostSeg, and Cost Seg EZ publish specific per-study pricing. KBKG, ETS, Capstan, CSSI, and Madison SPECS use consultative quoting — every number for those firms will come from a conversation. Always get a written quote before assuming a figure applies to your property. Figures above reflect vendor-published pricing current as of the publish date at the top of this page.
Firm-by-firm breakdown
1. KBKG (kbkg.com)
What they offer. Engineer-signed cost segregation studies, R&D tax credit, 179D, 45L, repair-vs-capitalization consulting, and transfer pricing. Headquartered in Pasadena, California; founded 1999; seven additional US offices (Los Angeles, New York, Atlanta, Chicago, Dallas, Detroit, Houston). Public materials report more than $11 billion in tax credits and incentives delivered to clients.
Customer type. Post-close owner. KBKG's own cost segregation page states the firm's offering is built for properties with depreciable basis above $1.5 million. Primary distribution is through CPA firms. Pricing is custom-quoted and not published.
2. Engineered Tax Services / ETS (engineeredtaxservices.com)
What they offer. Engineer-signed cost segregation studies, R&D tax credit, 179D, 45L, grant services, and tangible property regulations consulting — cost seg bundled with the full engineering-based tax incentive menu. Headquartered in West Palm Beach, Florida.
Customer type. Post-close owner. Mid-market to enterprise owners or CPA clients who have more than one engineering-based tax incentive to pursue in a single engagement (for example, cost seg plus R&D credit on a build-out, or cost seg plus 179D on larger multifamily). Pricing is custom-quoted and not published.
3. Capstan Tax Strategies (capstantax.com)
What they offer. Engineer-signed cost segregation studies, 179D energy-efficient buildings deduction, 45L, and tangible property analysis (TPA) consulting. Philadelphia area.
Customer type. Post-close owner. Multifamily and commercial owners who need tangible-property-regs work layered with the cost seg study (for example, properties with a history of improvements, dispositions, or partial retirements). Short-term rental coverage exists on the site but is lighter than the residential-focused firms below. Pricing is custom-quoted and not published.
4. CSSI — Cost Segregation Services, Inc. (costsegregationservices.com)
What they offer. Engineer-signed cost segregation studies distributed primarily through a national CPA and financial advisor referral network, with standardized deliverable format and IRC §481(a) look-back / change-in-accounting-method support. Headquartered in Louisiana. Public materials report more than 45,000 studies completed.
Customer type. Post-close owner. CPAs placing multiple studies through a referral channel, portfolio owners, and investors doing look-back studies on properties placed in service in prior years. Pricing is custom-quoted and not published.
5. Madison SPECS (madisonspecs.com)
What they offer. Engineer-signed cost segregation studies at institutional and portfolio scale. Part of Madison Commercial Real Estate Services, headquartered in the New Jersey area.
Customer type. Post-close owner. Institutional and larger-portfolio owners who need standardized studies across many assets. Individual single-property STR investors are not the firm's center of gravity. Pricing is custom-quoted and not published.
6. R.E. Cost Seg (recostseg.com)
What they offer. Two engineer-signed cost segregation products: a Rapid Report starting at $950 for sub-$1.2M residential (single-family through 4-unit, cap-ex under $80K), and a Fully Engineered study starting at $2,320 for residential and $2,730+ for commercial. Houston, Texas. Marketing explicitly covers Airbnb and short-term rentals.
Customer type. Post-close owner. Residential and small-portfolio owners who want published flat-fee pricing on a straightforward property. Complex properties, major renovations, or commercial-scale work move to the Fully Engineered tier.
7. FreeCostSeg / Modern CFO (freecostseg.com)
What they offer. Flat-fee engineer-signed cost segregation studies, $1,200–$5,000 (most single-family residential $1,200–$1,600), with sign-off from an ASCSP-member professional (Matthew Gigantelli, M009-25) and an AI-assisted intake workflow. Instant online benefit estimator on the home page. Lifetime IRS defense bundled into the paid product. Founded 2024.
Customer type. Post-close owner. Residential owners — particularly STR / Airbnb owners — who have closed on the property and want the lowest-priced engineer-signed study available. FreeCostSeg also publishes a free pre-purchase calculator; see the DepreciMax comparison below for how property-specific analysis differs from a general-stats calculator.
8. Cost Seg EZ (costsegez.com)
What they offer. A three-tier product: a DIY tier, an Engineer-Reviewed tier (around $895 for residential under $1M), and a Fully Engineered tier (from around $2,500 residential). Princeton, New Jersey. Short-term rental is listed as a supported property type.
Customer type. Post-close owner. Residential owners who want to pick an output tier (DIY, engineer-reviewed, or fully engineered) based on how much deduction they expect and how much engineer involvement their CPA requires. Cost Seg EZ also publishes a free pre-purchase Estimate; see the DepreciMax comparison below for the general-stats vs property-specific distinction.
A note on firms not included. This roundup covers eight firms common in STR investor and CPA conversations. It is not exhaustive. Software-only tools like Cost Seg Smart play adjacent roles, and Big 4 and regional accounting firms also offer cost segregation. If a firm you've been quoted isn't listed above, that does not imply anything about fit for your property.
Screen the property before you hire the firm
How much does a cost segregation study cost for a short-term rental?
Public pricing for single-family short-term rental studies in 2026 lands in a surprisingly tight band once you filter for engineer-signed deliverables. Cost Seg EZ's Engineer-Reviewed tier starts around $895, R.E. Cost Seg's Rapid Report starts at $950, and FreeCostSeg starts at $1,200. The top of the published-pricing range sits around $5,000 for a Fully Engineered FreeCostSeg study, with R.E. Cost Seg's Fully Engineered residential tier at $2,320+ and commercial at $2,730+.
Above that published-pricing tier, the five custom-quote firms (KBKG, ETS, Capstan, CSSI, Madison SPECS) do not publish per-study rates. Industry-typical ranges for single-family residential engagements through those firms generally fall between $3,000 and $10,000+, with pricing scaling by property size, complexity, portfolio status, and the depth of audit-defense support bundled. For luxury vacation homes, multifamily, or commercial engagements, quotes land higher — sometimes meaningfully higher.
For a deeper breakdown of pricing by property type and property class, see our full walk-through of cost segregation study cost in 2026.
When a formal cost segregation study is worth it — and when it isn't
The CPA rule of thumb is that a cost segregation study fee should not exceed roughly 5–10% of the Year-1 tax savings the study unlocks. That math gives you three bands on an STR purchase:
Under $500,000 basis. Year-1 bonus depreciation on a $400K STR with a 25% land ratio and the full OBBBA 100% bonus rate typically lands in the $60K–$80K range. A $900–$2,500 published study clears the 5% threshold comfortably; a $5,000+ custom-quote study starts bumping into the ceiling. This is the band where published-pricing firms are usually the right call.
$500,000 – $1,000,000 basis. Year-1 write-off scales into the $100K–$200K range on a typical STR, which opens the budget for a Fully Engineered study from any of the eight firms. Most sub-$1.5M properties sit in this band, and most of the published-pricing firms are a defensible choice. Custom-quote firms become competitive here if a CPA has an existing relationship.
Above $1,500,000 basis. This is KBKG's stated floor — the band where their custom-quote pricing structure actually fits the economics of the engagement. Luxury vacation homes, large multifamily, mixed-use, and complex properties all sit here. A $7,500 KBKG, CSSI, Madison SPECS, or Capstan engagement is well inside the 5% guardrail on a Year-1 deduction of $200K–$500K+.
For a longer look at the decision framework, see our is a cost segregation study worth it for an Airbnb walk-through.
Where DepreciMax fits — the pre-purchase lane
Every firm above is engaged by an owner after close. DepreciMax is engaged by a buyer, before the offer. The question changes: not “given this house I own, how much can I write off?” but “which of these candidate houses produces the strongest Year-1 math — and which, if any, should I write an offer on?”
The tool: paste a property address, get a Year-1 bonus depreciation estimate from Claude Opus analysis of 7–25 listing photos, closely calibrated to a formal engineered study. $99 per property; $249/mo Pro for unlimited reports (3-month minimum).
DepreciMax does not replace any of the firms above. After a buyer closes, the formal cost segregation study still gets commissioned from one of them — which firm depends on property size and the buyer's CPA relationship, per the sections above. The two tools stack in sequence: pre-purchase screen first, post-purchase formal study after close.
DepreciMax vs. the free pre-purchase calculators
DepreciMax is not the only pre-purchase tool in the market. Cost Seg EZ, Cost Segregation Guys, and FreeCostSeg all publish free pre-purchase calculators as well. The key difference is what the tool actually looks at before producing a number:
| Pre-purchase tool | What it analyzes | Output | Price |
|---|---|---|---|
| DepreciMax | Property-specific: 7–25 of the actual listing photos (interior, exterior, outdoor amenities), the actual property address + county assessor land ratio, and the actual listing details. Claude Opus classifies the real finishes, appliances, and 15-year land improvements the buyer sees in the photos. | Year-1 bonus depreciation estimate specific to that property, with land-ratio range and tier context across 197 US STR markets. | $99 / property |
| Cost Seg EZ Free Estimate | General-stats: a handful of typed inputs (purchase price, year built, property type, square footage). No analysis of the actual property's finishes or amenities. | Regional-average deduction range for a property with those typed characteristics. Lead-gen for the firm's paid study. | Free (lead-gen) |
| Cost Segregation Guys Free Proposal | Rep-reviewed general-stats: similar typed inputs plus five-hour rep review. Still no actual-property analysis before the number is generated. | Rep-generated estimated Year-1 savings range + flat quote for the paid study. | Free (lead-gen) |
| FreeCostSeg Free Calculator | General-stats: typed inputs (purchase price, property type, zip). Returns an instant estimate without looking at the actual property. | Estimated benefit range + flat-fee quote for FreeCostSeg's paid study. | Free (lead-gen) |
The free calculators and DepreciMax both run before close, but they are solving different problems. If a buyer wants a rough industry-average number on one specific property they already have under contract, the free calculators are fine — faster and no cost. If a buyer is comparing candidate properties and the per-property number has to be based on the actual listing (not an industry average), the general-stats calculators flatten too much of the signal: two properties with identical sqft and purchase price can produce very different Year-1 deductions depending on their actual finishes, outdoor amenities, and land ratio, and that difference is what the pre-offer decision turns on.
When DepreciMax is the wrong tool
- You only need a rough industry-average number. The free calculators from Cost Seg EZ, Cost Segregation Guys, and FreeCostSeg give that for $0.
- You're a long-term rental investor and not a real estate professional. The §469(c)(7) seven-day average-stay rule is what unlocks the outsized Year-1 deduction against non-passive income for most STR investors. If your average stay is longer than seven days, the STR pathway does not apply. The exception: if you qualify as a real estate professional under IRC §469(c)(7)(B), you can still use cost segregation to offset non-passive income from your long-term rentals — and DepreciMax works for screening those properties too.
Screen your next STR before you write the offer — $99
Paste any short-term rental address. Get a Year-1 bonus depreciation estimate from listing-photo AI analysis — in under 10 minutes. Then hire one of the firms above after you close.
Run a Property Report — $99 →Frequently Asked Questions
What is the best cost segregation firm for a short-term rental?
The right firm depends on property size. For short-term rentals under about $1.5M, firms with published flat-fee pricing like R.E. Cost Seg, FreeCostSeg, and Cost Seg EZ typically fit best. For portfolios or properties above $1.5M, KBKG, Engineered Tax Services, Capstan Tax Strategies, and Madison SPECS carry the bench for complex engagements. Before hiring, use a pre-offer tool like DepreciMax to screen whether a formal study is even worth commissioning.
How much does a cost segregation study cost for an Airbnb?
For single-family short-term rentals, publicly published pricing runs roughly $900 to $5,000 flat-fee, with most residential studies landing between $1,200 and $2,500. R.E. Cost Seg's Rapid Report starts at $950, FreeCostSeg at $1,200, and Cost Seg EZ's Engineer-Reviewed tier around $895. Larger multifamily or commercial STRs are custom-priced by the firm.
Which cost segregation firm is cheapest for an Airbnb?
Based on publicly published pricing, the lowest entry points for a single-family short-term rental are Cost Seg EZ's Engineer-Reviewed tier (around $895), R.E. Cost Seg's Rapid Report (starting $950), and FreeCostSeg (starting $1,200). Enterprise firms like KBKG, Engineered Tax Services, Capstan Tax Strategies, CSSI, and Madison SPECS use custom-quote pricing and typically land higher.
Is a cost segregation firm necessary for a $500,000 short-term rental?
Not always. Below $500,000 basis, the study fee can eat a meaningful share of Year-1 tax savings. Many short-term rental owners at this basis use a lower-cost residential-focused firm or validate the opportunity with a pre-offer tool like DepreciMax before deciding whether a formal study clears their break-even threshold.
What is the difference between a cost segregation firm and cost segregation software?
A firm delivers an engineer-signed, IRS-aligned study you file with your return and defend in an audit. Software or AI tools generally produce an estimate or a DIY output. For audit defense, you want a signed engineering study. For pre-offer screening or back-of-envelope planning before you buy, software is faster and cheaper.
Does DepreciMax replace a formal cost segregation study?
No. DepreciMax is a pre-offer screening tool that estimates Year-1 bonus depreciation from listing photos before you buy. Once you own the property and are ready to file, you still want a formal, engineer-signed cost segregation study from one of the firms in this roundup.
Which cost segregation firm is best for a portfolio of short-term rentals?
For five or more properties or multi-market portfolios, Madison SPECS, KBKG, and Engineered Tax Services have the operational bench for volume engagements. CSSI runs the highest-volume residential practice via its CPA referral channel. R.E. Cost Seg and FreeCostSeg handle portfolio work at lower price points for smaller SFR portfolios.
How long does a cost segregation study take?
Most residential short-term rental studies run two to six weeks from site data submission to delivered report. Faster rapid or software-assisted products from R.E. Cost Seg, Cost Seg EZ, and FreeCostSeg can turn around in days. Enterprise firms handling complex commercial engagements may take six to twelve weeks.
Do cost segregation studies trigger an IRS audit?
No evidence links a properly executed cost segregation study to elevated audit risk. The IRS publishes a Cost Segregation Audit Techniques Guide; studies prepared in accordance with it are standard practice for income-producing real estate across the country.
Can I use a cost segregation firm for a property I bought years ago?
Yes. A look-back study lets you catch up missed depreciation via a Form 3115 change in accounting method, without amending prior returns. All eight firms in this roundup handle look-back studies for short-term rentals and other income-producing property.
Sources & further reading
Firm facts in this roundup were sourced from each firm's public materials as of the publish date at the top of the page. For CSSI and Madison SPECS, some current public claims could not be independently re-verified against the live site during fact-check; language in those sections hedges where appropriate. Verify any pricing or feature claim before signing a letter of engagement with any firm.
- KBKG — Cost Segregation: kbkg.com/cost-segregation · kbkg.com/about
- Engineered Tax Services: engineeredtaxservices.com
- Capstan Tax Strategies: capstantax.com/about-us
- CSSI (Cost Segregation Services, Inc.): costsegregationservices.com
- Madison SPECS: madisonspecs.com
- R.E. Cost Seg: recostseg.com
- FreeCostSeg (Modern CFO): freecostseg.com
- Cost Seg EZ: costsegez.com
- IRS — Cost Segregation Audit Techniques Guide: irs.gov cost segregation ATG
- IRS Publication 946 — How to Depreciate Property: irs.gov/publications/p946
Firm names, pricing, and feature descriptions were current as of the publish date and were sourced from each firm's public website. Nothing in this article is tax, legal, or engagement advice — confirm your situation with a licensed CPA and get a written quote from any firm before signing.