This is the question we get most often: "How many years of missed depreciation can I actually claim?" The short answer is going to surprise you. The long answer is the difference between leaving $40K on the table and recovering it.
The short answer
All the way back to the year you placed the property in service. If you bought a rental in 2014 and never did cost segregation, you can use Form 3115 §481(a) in 2026 to catch up twelve years of missed accelerated depreciation. There is no 3-year limit. There is no statute-of-limitations limit. Form 3115 has no cap on how far back the catch-up reaches.
The catch is: this only works for property you still own. For property already sold, the limit is 3 years (via Form 1040X amended returns).
Why most owners think the limit is 3 years
The 3-year figure comes from the IRS statute of limitations on amending tax returns. IRC §6511(a) says you generally have 3 years from the original filing date to amend a return. That cap applies to Form 1040X amendments — not to Form 3115 method changes.
The two forms are doing different things:
- Form 1040X reopens a specific prior year's return. Subject to the 3-year statute.
- Form 3115 doesn't reopen any prior return. It computes a single §481(a) catch-up adjustment in the current year. The current year's return is the only one being filed.
Because Form 3115 doesn't touch prior years, the 3-year amendment statute doesn't apply. The IRS published this rule in Rev. Proc. 2007-16 and reaffirmed it in subsequent revenue procedures (most recently Rev. Proc. 2022-14, which is the current automatic-consent procedure for accounting method changes).
Why the IRS allows this
The policy logic: depreciation errors compound year after year. If a taxpayer was on the wrong method for ten years, forcing them to amend ten returns is administratively expensive for everyone — the taxpayer, the CPA, the IRS. §481(a) gives the IRS a clean accounting tool: compute the cumulative effect of the method change, book it once in the current year, and move on. It's faster, cleaner, and produces the same final tax result.
The IRS issued Rev. Proc. 87-56 (the automatic depreciation tables), Rev. Proc. 2007-16 (depreciation method changes specifically), and Rev. Proc. 2022-14 (the current omnibus procedure) all to streamline this. Cost segregation method changes are explicitly listed as DCN 7 in the current procedure — automatic consent, no user fee, no advance approval.
Practical limits: when does the math stop being worth it?
While there's no legal cap on years, there's a practical cap: at some point, the catch-up becomes small relative to the effort and cost. Here's the rough rule of thumb:
| Years held | Practical assessment |
|---|---|
| 0–1 | Don't bother with 3115 — just elect cost seg on this year's return |
| 2–3 | MAYBE — catch-up is modest. Run the calculator before committing. |
| 4–7 | Sweet spot. Catch-up typically 3–5× a forward-only study. |
| 8–10 | Strong YES. The longer the hold, the bigger the catch-up. |
| 10+ | Strong YES, but residential property close to the 27.5-year mark has less remaining basis to accelerate — still positive but plateauing. |
Edge case 1: properties placed before 2018
The Tax Cuts and Jobs Act (effective January 1, 2018) introduced 100% bonus depreciation. Properties placed in service in 2017 or earlier got 50% bonus instead. The catch-up is still substantial but proportionally smaller because the bonus rate is half.
Example: $400K building basis with 22% reclass = $88K of accelerated property. At 100% bonus: $88K immediate deduction. At 50% bonus: $44K immediate + the rest depreciated over 5/15 years. The 50%-bonus catch-up still produces meaningful tax savings, but the leverage is roughly half.
Edge case 2: 2024 and later placements (declining bonus)
The TCJA's 100% bonus depreciation phased down on a published schedule:
- 2018–2022: 100%
- 2023: 80%
- 2024: 60%
- 2025: 40%
- 2026 and forward: 20% (currently scheduled)
For lookback studies on properties placed in 2024 or 2025, the catch-up is smaller per dollar of reclassified basis because the bonus rate is lower. But these are also recent properties — you may have only 1–2 years of missed depreciation, so the absolute catch-up is modest regardless.
The OBBBA legislative wrinkle: The One Big Beautiful Bill Act (signed July 2025) permanently restored 100% bonus depreciation for property placed in service in 2025 and later. If your property qualifies under OBBBA, the bonus rate flips back to 100% — see your CPA for whether your property qualifies.
Run the calculator on the homepage to see your estimated Year-1 catch-up deduction and federal tax savings before you commit to a study.
Run the calculator Order a lookback studyEdge case 3: the property has changed use
If a property started as a primary residence and later converted to a rental, the depreciation clock starts at the conversion date — not the original purchase date. The "year placed in service" for cost seg purposes is when you first used it as income property. Catch-up runs from there.
Edge case 4: you've already done cost seg, but on a partial method
Some taxpayers did cost seg years ago that captured only some of the available reclassification (e.g., 5-year property only, no 15-year land improvements). A second §481(a) adjustment can capture the missing buckets. This is rare but legal under DCN 7.
Edge case 5: the property was inherited
Inherited property gets a stepped-up basis to fair market value at the date of inheritance. The depreciation clock restarts at that date. Lookback applies from the inheritance date forward, not from the original purchase by the decedent.
The "claim everything you can" argument
Because Form 3115 has no cap, there's no penalty for claiming the full catch-up. The math nets out: every dollar of accelerated depreciation you claim now reduces basis (and increases potential recapture if you later sell). But:
- The deduction is worth more today than the recapture is worth later (time value of money).
- Recapture is taxed at 25% maximum (§1250 unrecaptured gain rate), which is lower than most ordinary income brackets.
- If you 1031-exchange, recapture is deferred indefinitely.
- If you die holding the property, basis steps up and recapture disappears.
For most investors, "claim every dollar of catch-up Form 3115 allows" is the right play. Talk to your CPA about your specific recapture exposure if you plan to sell soon — that's the one scenario where capping the catch-up could make sense.
Bottom line
Form 3115 has no statute of limitations on how far back you can catch up missed depreciation. Whether you bought your rental 2 years ago or 12 years ago, the same form captures the entire cumulative shortfall as a single Year-1 deduction. The 3-year rule everyone repeats applies only to amended returns (Form 1040X), which only matter for property you've already sold.
If you've owned a rental 3+ years and never did cost seg, the calculator on the homepage will show you the catch-up estimate in 30 seconds. Read the filing guide for the next step.