ADU Cost Segregation Study
A full engineering-based analysis of your accessory dwelling unit that reclassifies building components into 5-, 7-, or 15-year depreciation schedules, dramatically accelerating your deductions and boosting cash flow.
ADUs are one of the most overlooked opportunities for accelerated tax depreciation. Whether you've built a backyard cottage, garage conversion, or detached guest suite, Seneca Cost Segregation's engineering-based studies reclassify your ADU's components to unlock front-loaded deductions turning 20–40% or more of your property costs into immediate, IRS-compliant tax savings.
Comprehensive cost segregation solutions designed to maximize tax savings for accessory dwelling unit owners across all 50 states.
A full engineering-based analysis of your accessory dwelling unit that reclassifies building components into 5-, 7-, or 15-year depreciation schedules, dramatically accelerating your deductions and boosting cash flow.
Already own your ADU? Claim all missed depreciation from the past 15 years in a single tax year using IRS Form 3115 no amended returns required, with the same rigorous engineering analysis.
A convenient 30–45 minute video-call inspection of your ADU eliminates the need for costly on-site visits, delivering faster turnaround in 2–3 weeks while keeping study costs affordable.
Every ADU cost segregation study includes Seneca's AuditDefense guarantee comprehensive IRS audit support at no additional charge for as long as you own the property, backed by a potential study cost refund.
Post-study implementation support ensures your CPA can seamlessly integrate ADU depreciation schedules into your tax returns, with Seneca's team available to answer technical questions throughout the process.
Need your ADU cost segregation study completed before a tax deadline? Expedited service delivers fully engineered reports in as little as one week to meet your most urgent timing requirements.
We assess your ADU's eligibility, estimate your potential first-year tax savings, and walk you through expected ROI completely free. Most ADU owners are surprised to learn how much accelerated depreciation they qualify for, even on smaller structures.
See how ADU and real estate property owners have unlocked significant tax savings with Seneca Cost Segregation.
"We contacted Seneca for a Cost Seg Study and they went above and beyond. Their eagerness to help and province of info will blow you away."
"I couldn't be more pleased with the results. Their team was incredibly professional, prompt, and easy to work with. I achieved a highly favorable tax situation and recommend Seneca to anyone looking to maximize their tax benefits."
"Dylan and his team at Seneca Cost Segregation are extremely knowledgeable. When I explored their website, it was clear they knew their stuff. It offered a very professional approach to cost segregation, backed by years of experience."
"We contacted Dylan for a cost seg study and he went above and beyond Not only will their pricing be the best price you will find, his eagerness to help and province info will blow you away"
"The tax savings achieved with Seneca Cost Segregation made a major impact on my bottom line. I wasn't aware it was a possibility until they brought the opportunity to me. Their insight and expertise are invaluable."
"Their team was incredibly professional, prompt, and easy to work with."
"Seamless experience with great results. Highly recommend!"
"I've referred multiple clients to Seneca, and each time they uncovered significant tax savings. Their team is fast, professional, and easy to work with. They've become a trusted extension of our tax strategy."
"Extremely professional and efficient in their cost set analysis. Great communication and transparency. Will be using them going forward on all my properties."
"We contacted Seneca for a Cost Seg Study and they went above and beyond. Their eagerness to help and province of info will blow you away."
"I couldn't be more pleased with the results. Their team was incredibly professional, prompt, and easy to work with. I achieved a highly favorable tax situation and recommend Seneca to anyone looking to maximize their tax benefits."
"Dylan and his team at Seneca Cost Segregation are extremely knowledgeable. When I explored their website, it was clear they knew their stuff. It offered a very professional approach to cost segregation, backed by years of experience."
"We contacted Dylan for a cost seg study and he went above and beyond Not only will their pricing be the best price you will find, his eagerness to help and province info will blow you away"
"The tax savings achieved with Seneca Cost Segregation made a major impact on my bottom line. I wasn't aware it was a possibility until they brought the opportunity to me. Their insight and expertise are invaluable."
"Their team was incredibly professional, prompt, and easy to work with."
"Seamless experience with great results. Highly recommend!"
"I've referred multiple clients to Seneca, and each time they uncovered significant tax savings. Their team is fast, professional, and easy to work with. They've become a trusted extension of our tax strategy."
"Extremely professional and efficient in their cost set analysis. Great communication and transparency. Will be using them going forward on all my properties."
"We contacted Seneca for a Cost Seg Study and they went above and beyond. Their eagerness to help and province of info will blow you away."
"I couldn't be more pleased with the results. Their team was incredibly professional, prompt, and easy to work with. I achieved a highly favorable tax situation and recommend Seneca to anyone looking to maximize their tax benefits."
"Dylan and his team at Seneca Cost Segregation are extremely knowledgeable. When I explored their website, it was clear they knew their stuff. It offered a very professional approach to cost segregation, backed by years of experience."
"We contacted Dylan for a cost seg study and he went above and beyond Not only will their pricing be the best price you will find, his eagerness to help and province info will blow you away"
"The tax savings achieved with Seneca Cost Segregation made a major impact on my bottom line. I wasn't aware it was a possibility until they brought the opportunity to me. Their insight and expertise are invaluable."
"Their team was incredibly professional, prompt, and easy to work with."
"Seamless experience with great results. Highly recommend!"
"I've referred multiple clients to Seneca, and each time they uncovered significant tax savings. Their team is fast, professional, and easy to work with. They've become a trusted extension of our tax strategy."
"Extremely professional and efficient in their cost set analysis. Great communication and transparency. Will be using them going forward on all my properties."
Over 10,200+ engineered cost segregation studies completed across the United States. Average first-year tax deduction: $171,243
Studies Completed
Avg Tax Savings
Partners
"I've referred multiple clients to Seneca, and each time they uncovered significant tax savings. Their team is fast, professional, and easy to work with. They've become a trusted extension of our tax strategy."
Eliot Varnum CPA, Varnum, Finch & Co. "Every client we send their way whether it's their first cost segregation study or their seventh is treated like their most important client. Their team's attention to detail, responsiveness, and genuine commitment to adding value set them apart."
Matt Bontrager CEO, Truebooks CPA We combine engineering precision, real estate investor expertise, and a client-first approach to deliver ADU cost segregation studies that stand up to IRS scrutiny and maximize your returns.
Every ADU study is built on rigorous engineering methodology and proprietary technology, ensuring IRS-compliant, audit-ready results.
Our founders are real estate investors themselves they understand ADU ownership challenges and structure studies to maximize your after-tax cash flow.
With engineers deployed across all 50 states and virtual tours available anywhere, we serve ADU owners in every market, from dense urban areas to rural properties.
Every ADU study includes lifetime IRS audit defense at no extra cost backed by a money-back guarantee if the study has a material issue.
Real estate investors and engineers committed to maximizing your ADU tax savings.
Co-Founder and CEO
Dylan Scandalios is an active investor in multi-family properties in the Pacific Northwest and a recognized Cost Segregation Expert. Before founding Seneca Cost Segregation, Dylan closed millions of dollars in business for both public and private companies along the West Coast, developing deep expertise in real estate finance and tax strategy. As CEO, Dylan has helped thousands of real estate investors including office building owners save millions on their federal taxes through engineering-based cost segregation studies. His hands-on investment background means he approaches every client engagement with the perspective of an investor, not just a service provider. Under his leadership, Seneca has completed over 10,200 studies nationwide and achieved a 95% client referral rate.
Co-Founder
Paul Spies is a Marine Corps Sergeant who brings over 8 years of hands-on expertise in real estate construction to Seneca Cost Segregation. As a Principal Broker and Licensed Contractor, Paul successfully flipped over 150 homes in just four years and led ground-up multi-family development projects across the country. Having leveraged cost segregation personally since 2018 to maximize returns on his own office and residential properties, Paul co-founded Seneca to make the same powerful tax strategy accessible to investors nationwide at an affordable price point and delivered on time. His construction background gives Seneca a unique engineering advantage when analyzing complex office building components and systems.
Chairman
Howard Hirsch serves as Chairman of Seneca Cost Segregation, providing executive leadership and strategic oversight to the firm's continued national expansion. With deep experience in financial services and real estate advisory, Howard helps guide Seneca's direction as it scales its engineering-based cost segregation services to property owners across all 50 states, including California's dynamic real estate market. His leadership ensures the company maintains its commitment to technical excellence, client satisfaction, and IRS-compliant study delivery that protects clients through every phase of property ownership.
President/Treasurer
Harry Papp serves as President and Treasurer of Seneca Cost Segregation, overseeing the company's operational and financial integrity. His dual role ensures that client investments in cost segregation studies generate maximum ROI through rigorous financial management and disciplined operational processes. Harry's leadership directly supports Seneca's ability to deliver studies on time and within budget a standard that has helped the firm achieve a 95% client referral rate and an average first-year deduction of $171,243 for property owners across California and the rest of the nation.
Merle Rosskam
CEO
Yes, absolutely. Accessory dwelling units including detached cottages, garage conversions, basement apartments, and guest suites are eligible for cost segregation studies just like larger rental properties. Our engineering team identifies and reclassifies depreciable components of your ADU into 5-, 7-, or 15-year categories, accelerating deductions that would otherwise be spread over 27.5 years.
Talk to one of our cost segregation experts for a free consultation and personalized savings estimate.
Seneca Cost Segregation serves ADU owners across all 50 states with virtual and on-site study options.
All 50 States
Service Area
10,200+
Studies Completed
95%
Client Referral Rate
We serve ADU owners in all 50 states, virtually or on-site. Let's confirm coverage and get started.
Certified Cost Segregation Professional designation from ASCSP
Perfect five-star rating from satisfied clients nationwide
Proudly veteran-owned, delivering disciplined and reliable service
Tell us about your accessory dwelling unit and we'll provide a no-obligation savings estimate and ROI analysis typically within one business day. Our team is ready to help you keep more of what you've earned.
For immediate assistance, feel free to give us a direct call at +1 530-797-6539. You can also send us a quick email at info@senecacostseg.com.
For immediate assistance, feel free to give us a direct call at +1 530-797-6539. You can also send us a quick email at info@senecacostseg.com.