If you own California residential rental property, the timing of a cost segregation study can affect when you claim depreciation deductions and capture potential federal tax benefits. Residential rental buildings generally use a 27.5-year recovery period, while qualifying components can fall into shorter five- or 15-year categories. The result can accelerate deductions, although California does not conform to federal bonus depreciation.
Why Timing Matters
California cost segregation can produce different federal and state depreciation results. For federal purposes, a study can identify components qualifying for five- or 15-year recovery periods, potentially accelerating deductions compared with the building’s 27.5-year schedule.
California generally conforms to federal MACRS rules under its personal income tax law as of January 1, 2025, but important differences remain. California does not conform to federal bonus depreciation under IRC Section 168(k), so state and federal calculations can diverge. The IRS guidance and applicable federal law should be reviewed before projecting a tax benefit.
California also does not conform to IRC Sec. 469(c)(7), so for California purposes all rental activities remain passive regardless of real estate professional status.
Acquisition-Year Timing
When you acquire a residential rental property, completing a study in the acquisition year can provide a cleaner starting point for depreciation. Closing documents, improvement records and the placed-in-service date are generally easier to assemble at that stage.
Placed in service generally means the property is ready and available for its intended use, which matters when determining when depreciation begins. The acquisition year can therefore be a practical point to establish the property’s depreciable basis and identify qualifying shorter-life components.
Consider a California investor who acquires a residential rental property for $2,400,000, of which $600,000 is allocated to land, leaving a depreciable building basis of $1,800,000. The investor separately purchases $80,000 of furniture, fixtures and equipment. The property is placed in service in January. Without a cost segregation study, the building is depreciated over 27.5 years and the first-year deduction under the mid-month convention is $62,730; the separately purchased FF&E receives 100% bonus depreciation of $80,000 whether or not a study is performed, for a total of $142,730. With a study, $216,000 is reclassified to five-year personal property and $180,000 to 15-year land improvements, giving $396,000 of accelerated basis eligible for 100% bonus depreciation. The remaining $1,404,000 stays on the 27.5-year schedule and produces $48,929 in year one. Adding the $80,000 of FF&E, the first-year deduction is $524,929. The study’s incremental contribution is $382,199, which at a 37% marginal federal rate defers roughly $141,414 of tax.
Passive Activity Limits
These deductions are not automatically usable. Under IRC Sec. 469, rental real estate is generally a passive activity and passive losses offset only passive income; unused losses are suspended and carried forward until the taxpayer has passive income or disposes of the activity in a fully taxable transaction. A taxpayer who qualifies as a real estate professional under Sec. 469(c)(7) and materially participates may treat the losses as non-passive. Separately, a rental with an average guest stay of seven days or less is not a rental activity under Reg. Sec. 1.469-1T(e)(3)(ii)(A), so material participation alone can make the losses non-passive without real estate professional status.
Depreciation Recapture
Accelerated depreciation is a deferral, not forgiveness. On a taxable sale, depreciation claimed on the five- and 15-year property a study reclassifies is recaptured under IRC Sec. 1245 as ordinary income to the extent of depreciation taken, potentially at rates up to 37%, rather than the 25% maximum applying to unrecaptured Sec. 1250 gain on the building itself. A study therefore shifts part of future gain from Sec. 1250 to Sec. 1245 treatment. The net benefit depends on the time value of the deferral and the expected holding period and is generally weaker for property expected to be sold within a few years.
Form 3115 And Catch-Up Depreciation
Form 3115 becomes relevant when your look-back study involves a change in accounting method for depreciation. The IRS identifies depreciation changes involving the method, recovery period or convention as accounting method changes when appropriate; Schedule E addresses changes for depreciation or amortization.
A qualifying change can produce a section 481(a) adjustment, reconciling prior depreciation with the amount allowable under the proper method. If the adjustment is negative, it generally reduces taxable income in the year of change, so catch-up depreciation can provide a current deduction. If the adjustment is positive, it generally spreads across four tax years; specific rules can apply. Your tax adviser should determine which procedure fits your facts before filing Form 3115.
Current Law
The One Big Beautiful Bill Act (P.L. 119-21), signed July 4, 2025, made the 100% first-year bonus depreciation rate under IRC Sec. 168(k) permanent for qualifying property acquired and placed in service on or after January 20, 2025. Before that change the rate was phasing down on a fixed schedule of 80%, 60%, 40%, 20% and then 0%. Property acquired before January 20, 2025 remains subject to the phase-down percentage in effect at the time of acquisition.
For a California residential rental owner, the acquisition year and a later look-back can both be worthwhile points for review. The appropriate choice depends on the property’s basis, records, prior depreciation, passive activity position, expected holding period and the separate federal and California treatment.
