Cost Segregation Explained: Process, ROI, Timing, and Audit Defense

In this episode of the Tax Smart REI Podcast, Thomas Castelli and Nathan Sosa sit down with Edward Griffith, Hall CPA’s Director of Cost Segregation, to walk through cost segregation from start to finish. They break down what a cost seg study is, which properties tend to produce the best ROI, when to schedule a study, why onsite visits matter more than ever, and how bonus depreciation changes the planning conversation heading into 2025 and beyond.

What Is a Cost Segregation Study (and Why Investors Use It)

Edward defines cost segregation in practical terms: the goal is to move as many assets as possible out of the 27.5-year (residential) or 39-year (commercial) depreciation bucket and into shorter-life categories—primarily 5-year and 15-year property.

Instead of depreciating the entire building as one “blob,” a cost seg study breaks down the property into components, things like flooring, fixtures, certain electrical and plumbing elements, and other non-structural items that qualify for faster depreciation.

Why that matters: shorter depreciation lives often unlock larger deductions earlier, especially when bonus depreciation is available, creating significant tax savings for the right investor profile (REPS, short-term rental strategies, high-income years, etc.).

What Types of Properties Produce the Best ROI?

Edward explains that a big driver of cost seg results is whether the property includes site improvements, things tied to the land that can still be depreciated (even though land itself is not depreciable).

Higher ROI property types

• RV parks / mobile home parks: Often high reclassification percentages (Edward cites ranges that can be dramatically higher than typical residential) due to heavy land improvements and infrastructure.
• Industrial buildings with specialized systems: Can outperform more “plain vanilla” buildings depending on the equipment and build-out.
• Medical offices (and specialty buildouts): Often strong results due to specialized plumbing/electrical, buildouts, and systems.
• Middle-of-the-road
• Single-family rentals / houses: Commonly produce solid results, often driven by interior components plus any driveway, fencing, landscaping, or other site-related items.

Lower ROI

• Warehouses: Often lower because warehouses tend to be “a shell”—less interior buildout to reclassify. Site improvements (like parking lots) can increase the benefit, but the base building is typically limited.

What About Landscaping and Parking Lots?

A key clarification in the episode: while land itself isn’t depreciable, land improvements often are.

Edward gives examples like:

• Landscaping work (sod, seeding, similar improvements)
• Parking lots and paved areas
• Other site improvements tied to the property’s use

He also makes an important practical point for investors running numbers: your cost seg percentage applies to purchase price minus land value, not the full purchase price. A beachfront property with a large land allocation may have a very different cost seg outcome than a similar-priced property where more value is assigned to improvements.

Onsite Study vs. “Software Study”: What’s the Difference?

The episode spends meaningful time on a growing concern in the cost seg world: the difference between quick software-based studies and defensible, documentation-heavy studies aligned with IRS expectations.

Why onsite visits matter

Edward explains that onsite work helps in two big ways:

1. Accuracy and detail: You can capture real measurements, materials, and actual conditions—often increasing the reclassification benefit.
2. Audit defense: The IRS has a clear set of expectations for what a “quality” report looks like, and onsite documentation helps check those boxes.

The IRS audit technique guide factor

Edward notes that the IRS uses a cost seg audit technique guide outlining what examiners want to see in a strong report. Many “quick and dirty” software studies can miss key elements such as:

• Clear methodology
• Adequate documentation
• Proper cost breakdown approaches

Bottom line: in 2025 and beyond, it’s a different landscape than it was 10–15 years ago, and investors should weigh audit defensibility more heavily when choosing a provider.

Timing: When Should You Do a Cost Segregation Study?

This is one of the most common cost seg questions, and Edward addresses several myths directly.

Myth: “You must do a cost seg before closing.”

Not true. You can only do a cost seg after you own the property anyway, and the study can be completed later.

Myth: “You must do a cost seg in the same year you bought the property.”

Also not true. Edward explains that lookback studies can be done later (e.g., a property acquired in earlier years), allowing investors to capture missed depreciation benefits.

Practical guidance

Edward’s general rule of thumb: aim to complete the study about a month before filing so your CPA team has time to implement it correctly.

Before or after renovations?

His “straight answer”: often after renovations, especially if renovations start immediately after purchase, because you want to avoid double-counting assets that were removed and replaced during construction.

They also briefly touch on the gray area around partial asset dispositions in the same year as placing a property in service, noting it’s commonly viewed as something most practitioners avoid in that scenario.

What the Cost Seg Process Looks Like at Hall CPA

Thomas asks the most practical question: “If I call Hall CPA for cost seg, what happens next?”

Edward lays out a straightforward workflow:

1. Intro call to understand the property and whether cost seg is a fit
2. Estimate of fee and expected benefits
3. Engagement letter if you move forward
4. Onsite visit to document the property
5. Report creation (often 50–70+ pages), built for both results and audit defense
6. Delivery + summary page (the key output your CPA team uses to file properly)

Typical timeline: roughly about a month start-to-finish in many cases.

What If You Bought Before Key Dates?

A major theme is the “question of the hour”: how bonus depreciation applies based on timing, contracts, and construction/improvements.
Edward’s high-level answer: it can be case-by-case, but there may be planning tools available, especially around improvements, such as:

• Breaking work into components based on when items were installed
• Reviewing construction timelines and safe harbor concepts
• Evaluating whether contracts are considered binding for the relevant rules

The takeaway: bring it to your advisory team early so it can be planned intentionally instead of discovered during filing.

Edward’s Best Advice for Investors Considering Cost Seg

Edward leaves investors with two practical pieces of guidance:

• Think about site improvements when buying. Properties with meaningful site work (parking, landscaping, infrastructure) often yield stronger results.
• Be mindful of audit risk and documentation quality. The cost seg landscape is more scrutinized now—so the quality of your study matters more than ever.

Final Note: Cost Seg Is Now In-House at Hall CPA

Thomas closes by sharing that Hall CPA now offers cost segregation in-house (at the time of recording, offered to clients), and encourages listeners who want to explore cost seg and broader tax strategy planning to book a discovery call to see if it’s a fit.

Disclaimer: This podcast summary was generated from the transcript and may contain some errors or miss key points from the audio recording.