Partial Asset Disposition Study: 2026 Step-by-Step Guide
A partial asset disposition (PAD) study lets you write off what's left of a building component you just tore out, so a rental property owner replacing a roof or HVAC system doesn't keep depreciating an asset that no longer exists.
- A partial asset disposition study writes off the remaining basis of a retired component the year you remove it.
- You need component-level cost data from a cost segregation study before you can calculate a PAD - Buy the study first.
- Missed a prior-year disposition? Form 3115 catches it up as an automatic accounting method change.
- 100% bonus depreciation applies to qualifying replacement components placed in service after January 19, 2025 under OBBBA.
- Document original cost, accumulated depreciation, and disposal date - this is the first thing an examiner asks for.
Why this matters
Without a partial asset disposition study, you keep depreciating a roof, water heater, or kitchen cabinet set that's sitting in a landfill. That's basis you're entitled to deduct now, not over the next 20 years.
Reg. §1.168(i)-8 lets owners of residential rental and short-term rental property write off the adjusted basis of a retired structural component in the year of disposal. Pair that with a cost segregation study for renovated and remodeled properties and the deduction stacks directly on top of whatever the original engineering-based study already reclassified.
For a short-term rental owner in the 37% bracket, a $28,000 remaining basis write-off is a $10,360 tax reduction the year it hits, not spread thin over decades.
What you'll need
- An existing engineering-based cost segregation study with component-level cost detail, or a plan to get one before the renovation starts
- Contractor invoices and permits showing the replacement date and cost
- Before-and-after photos of the disposed component
- Accumulated depreciation records for the retired asset
- A CPA who will make the election on the return for the year of disposition
- Access to virtualcostsegregation.com if you need the original component-level cost breakdown built first
The steps
1. Confirm you have component-level cost data
A PAD calculation is impossible without knowing what the retired component originally cost. If your property was never broken into structural components, roof, HVAC, cabinetry, flooring, decking, you're stuck estimating with an index method instead of a real number.
This is the single biggest reason PAD studies fail at audit: the owner never had a cost segregation study in the first place, so there's no basis to allocate. Order the study before the renovation, not after.
Common mistake: waiting until after demolition to ask what the roof cost. Once it's gone, you're relying on reconstructed estimates instead of contemporaneous data.
2. Identify the disposal event
A disposal event is the year you physically remove or replace a structural component, not the year you decide to renovate. Replacing a roof in March 2026 means the disposition happens on your 2026 return, even if you planned the job in 2025.
Write down the exact date the old component was removed. That date sets your depreciation cutoff for the retired asset.
3. Establish the original in-service cost of the retired component
Reg. §1.168(i)-8(f)(3) allows a handful of "reasonable methods" to determine the retired component's original cost: a cost segregation study allocation, a producer price index discounting method, or a pro rata allocation based on square footage.
An engineering-based cost segregation study is the strongest of these because it assigns an actual dollar figure to the roof, the HVAC unit, or the flooring at the time the property was placed in service, rather than backing into an estimate.
4. Calculate accumulated depreciation on the retired component
Depreciate the original component's cost from its placed-in-service date to its disposal date, using whatever class life it was assigned. A roof depreciates over 27.5 years as residential real property; certain land improvements or shorter-lived items already broken out in the segregation study depreciate faster.
Example: a roof allocated $40,000 in original cost, held 8 years on a 27.5-year straight-line schedule, has taken roughly $11,636 in depreciation. Adjusted basis at disposal: $28,364.
5. Write off the adjusted basis as an ordinary loss
The full $28,364 in the example above becomes a deductible loss in the year of disposal, reported on the return alongside your other rental activity. This isn't a capital loss subject to limits, it's an ordinary deduction tied to the disposed asset.
Buy this step into your annual tax planning if you renovate STR or long-term rental property on any regular cycle. Skip it only if the retired component's basis is immaterial, under a few hundred dollars, where the paperwork cost outweighs the benefit.
6. Capitalize the replacement and start new depreciation
The new roof, HVAC unit, or flooring gets capitalized and depreciated under its correct class life starting the day it's placed in service. If the replacement qualifies as a shorter-lived asset (many land improvements and certain fixtures do), bonus depreciation applies.
Under the One Big Beautiful Bill Act, bonus depreciation is restored to 100% for qualifying property placed in service after January 19, 2025. A new HVAC condenser classified with a recovery period of 20 years or less can be fully expensed in the year installed, on top of the loss you just took on the old one.
7. Make the partial disposition election on a timely filed return
The election is made by treating the disposed asset as disposed of on the return for that tax year, not by filing a separate form. Miss the window and you can't go back and amend your way into it retroactively the same way.
If you missed the election in a prior year and the old component is still sitting on your depreciation schedule as a "ghost asset," Form 3115 for catching up missed depreciation lets you correct it as an automatic accounting method change, no amended returns required.
8. Keep the paper trail
Hold onto the segregation study, contractor invoices, permit records, and photos for as long as the property is in service plus the statute of limitations. This is the file an examiner asks for first if the disposition gets questioned.
Get component-level cost data first
A flat-fee, engineering-based study is what makes a PAD calculable.
Troubleshooting
Problem: You never had a cost segregation study, so there's no component-level basis. Order one before you start the renovation if possible. If the component is already gone, a reasonable-method estimate (PPI discounting or square footage allocation) is your fallback, but it's a weaker audit position than contemporaneous engineering data.
Problem: You missed the election in a prior year. File Form 3115 as an automatic change in accounting method to catch up the missed deduction in the current year, no amended return needed.
Problem: The renovation looks like a "repair" rather than a disposition. A repair that doesn't remove and replace a whole structural component (patching part of a roof, for example) generally doesn't trigger a PAD. A full roof tear-off and replacement does.
Problem: Your CPA hasn't done a PAD before. Bring them the component-level cost breakdown and the disposal date. Most CPAs can run the calculation once they have real numbers instead of estimates.
Problem: You're combining a renovation with a 1031 exchange. Disposition timing and exchange timing interact. Get the 1031 exchange replacement property cost segregation guidance reviewed alongside your PAD before you close.
Problem: The property was refinanced right before the renovation. A cash-out refinance doesn't change the PAD math, basis and depreciation follow ownership, not financing. Don't let loan paperwork distract from the actual disposal date.
Tools and resources
- Cost segregation study for renovated and remodeled properties - component-level detail that makes PAD math possible
- How to catch up missed depreciation with Form 3115 - for prior-year dispositions you never elected
- How to read a cost segregation study report - find the component costs you need inside your existing study
- A CPA familiar with Reg. §1.168(i)-8 and Form 3115 filings
- Contractor invoices, permits, and dated photos for every disposed component
What to do next
If you're planning a renovation on a short-term or long-term rental this year, get the component-level cost breakdown locked in before demolition starts. Read accelerated depreciation for rental property owners for how PAD fits into your broader depreciation strategy across multiple properties.
FAQ
What is a partial asset disposition study?
A partial asset disposition study calculates the remaining tax basis of a building component you removed, like a roof or HVAC unit, so you can write it off as an ordinary loss instead of continuing to depreciate an asset that no longer exists. It requires component-level cost data, usually from an engineering-based cost segregation study.
Do I need a cost segregation study before I can do a partial asset disposition?
Yes, in practice. Without a component-level cost breakdown, you have no reliable basis figure to write off when you dispose of a roof, HVAC system, or flooring. A cost segregation study provides that original cost allocation.
When can I take a partial asset disposition deduction?
You take it in the tax year the component was physically removed or replaced, not the year you planned the renovation. The election is made on the timely filed return for that year.
What if I missed the election in a prior tax year?
File Form 3115 to catch up the missed depreciation as an automatic change in accounting method. This avoids amending prior-year returns.
Does bonus depreciation apply to the replacement component?
Yes, if the new component qualifies as personal property or a land improvement with a recovery period of 20 years or less. Under the One Big Beautiful Bill Act, bonus depreciation is 100% for qualifying property placed in service after January 19, 2025.
Is a partial asset disposition study the same as a full cost segregation study?
No. A cost segregation study reclassifies building components at the time you place a property in service. A partial asset disposition study uses that component data later, when you remove and replace a specific piece of the building.
Can I do a partial asset disposition on a short-term rental?
Yes. Airbnb and VRBO properties held as rental real estate qualify the same way as long-term residential rentals, provided you have the component-level cost data to support the calculation.
What documentation does the IRS want for a partial asset disposition?
The original component cost basis, accumulated depreciation to the disposal date, the disposal date itself, and contractor invoices or permits confirming the replacement. Photos of the old and new component help but aren't required.
One last thing
Most owners find the disposition loss on an old roof or HVAC system is worth more in year one than the depreciation they'd have collected on it over the next decade combined, because the write-off is immediate instead of spread over 27.5 years. Run the numbers before your next renovation, not after the dumpster's already been hauled away.