Section 179 and a New Commercial Roof: Federal and California Rules
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Last updated November 2026
Short answer: a new roof on a nonresidential building can qualify for Section 179 expensing on your federal return, but California allows far less. IRS Topic 704 lists roofs among the improvements to nonresidential real property that count as qualified real property, and the FTB caps California’s Section 179 deduction at $25,000.
This guide explains the rules in plain words so you can have a better conversation with your tax preparer. It is not tax advice.
Basics
What Section 179 is
Section 179 lets a business deduct the cost of qualifying property in the year it goes into service, instead of spreading the cost over many years. IRS Topic 704 says you deduct Section 179 expense in the year you place the qualifying property in service.
Most people know Section 179 for equipment and vehicles. Owners can also elect to treat some building improvements, including roofs, as Section 179 property.
Roofs
Does a roof count?
Yes, if it is a roof on nonresidential real property and the building was already in service. IRS Topic 704 defines qualified real property to include improvements made to nonresidential real property after it was first placed in service: roofs; heating, ventilation and air-conditioning property; fire protection and alarm systems; and security systems.
A few points follow from that wording:
- Nonresidential buildings. Warehouses, shops, retail, offices and similar buildings are the clear fit.
- Apartment buildings. The IRS wording covers nonresidential real property, so ask your preparer how an apartment or mixed-use building is treated before you count on the deduction.
- Existing buildings. The roof has to go on after the building was first placed in service. A roof on brand-new construction is part of the building.
- It’s an election. Topic 704 says you may elect to treat qualified real property as Section 179 property. Your preparer makes that choice on the return.
Repair
Repair or improvement?
A full roof replacement is an improvement, not a repair. IRS Publication 946 says that if you completely replace the roof, the new roof is an improvement because it is a restoration of the building.
That matters because repairs and improvements are handled differently on a tax return. Smaller leak repairs and maintenance may be treated another way. Keep invoices that describe the work clearly: what was replaced, how much of the roof, and why.
Federal
Federal limits for 2026
For tax years beginning in 2026, the federal Section 179 limit is $2,560,000, per IRS Revenue Procedure 2025-32. That limit shrinks dollar for dollar once the Section 179 property you place in service that year passes $4,090,000.
There is also a business income limit. IRS Topic 704 says the total you can deduct after the dollar limit is limited to your taxable income from the active conduct of a trade or business during the year.
For most small and mid-sized building owners, the dollar limit won’t be the problem. The income limit and the timing of the roof job usually matter more.
California
California’s much lower limit
California sets its own Section 179 numbers. The FTB’s 2025 Form 3885A instructions say the maximum Section 179 deduction for California purposes is $25,000. The same worksheet reduces that limit when the cost of Section 179 property placed in service passes $200,000.
The FTB instructions also note that federal and California limits may differ. In practice, a Stockton owner may deduct much more of a roof on the federal return than on the California return. The rest of the cost is depreciated on the state return over time.
What this means for planning: run the numbers for both returns. A roof that looks fully deductible federally can still leave most of its cost to depreciate for California.
Example
A simple example
Here is a made-up example, using only the federal and California limits above, to show how far apart the two returns can be. Say a business owner puts a $300,000 roof on a warehouse in 2026, and that roof is the only Section 179 property the business places in service that year.
- Federal: $300,000 is well under the $2,560,000 limit in Rev. Proc. 2025-32, so the dollar limit doesn’t get in the way. The deduction is still capped by the business income limit.
- California: under the FTB worksheet, the $25,000 limit is reduced by the amount over $200,000. Here that’s $100,000, which takes the California limit to zero.
Real returns have many more moving parts. Use this only to frame questions for your tax preparer.
Mistakes
Common mistakes
- Assuming the California return will match the federal one.
- Counting on Section 179 for an apartment building without checking how it’s classified.
- Forgetting the business income limit in a slow year.
- Booking a December finish that slips into January.
- Invoices that lump repairs and the new roof together with no clear scope.
Records
Records to keep
- The signed contract and the final invoice, with a clear scope.
- The permit and the final inspection sign-off.
- Photos before, during and after the work.
- The manufacturer and workmanship warranties.
- The date the roof was finished and put back in use.
Timing
Timing the roof job
Because Section 179 is tied to the year the roof is placed in service, timing matters. A job that wraps up in late December and one that finishes in early January land in different tax years.
- Ask the roofer for a realistic completion date, including inspections.
- Remember Stockton’s wet season. About 90% of the city’s rain falls November through April, per a National Weather Service study, so a late-fall start can slip.
- Keep the final invoice, the permit sign-off and photos of the finished roof together.
Ask
Questions to ask your tax preparer
- Does our building count as nonresidential real property for Section 179?
- Should we elect Section 179 for the roof, or depreciate it instead?
- How does the business income limit affect us this year?
- What will California allow, given its much lower Section 179 limit?
- Do we treat any of the work as a repair rather than an improvement?
Roofer
Questions to ask your roofer
- Can the invoice describe the scope clearly: full replacement, recover or repair?
- What is a realistic completion date, including inspections?
- Will you provide photos and a final sign-off when the roof is done?
See commercial roof replacement for what a reroof includes, and the cost guide for cited prices.
Sources
Where these rules come from
- IRS Topic No. 704, Depreciation: qualified real property, timing and the income limit.
- IRS Revenue Procedure 2025-32: 2026 dollar limits (section 4.24).
- FTB 2025 Form 3885A instructions: California’s $25,000 limit and $200,000 threshold.
- IRS Publication 946: why a full roof replacement is an improvement.
Tax rules change. Check the current versions of these sources, and talk to a qualified tax professional before you plan a purchase around them.
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