catchupdepreciation
Form 3115 §481(a) catch-up calculator

You bought your rental in 2022. The IRS owes you back-depreciation.

Form 3115 lets you claim every year of missed accelerated depreciation in a single tax year. Most owners discover $50K–$150K of unclaimed deductions on a property they already own.

The 30-second answer

Form 3115 §481(a) lets a property owner claim every year of missed accelerated depreciation in a single tax year — no amended returns required. On a $500,000 residential rental bought in 2022 and held 4 years, the catch-up adjustment typically lands between $60,000 and $120,000 in Year 1 deductions. At a 32% federal bracket, that's $19,000–$38,000 in tax savings claimed at once. Pre-2025 bonus depreciation rates (60–100%) often make a lookback study more valuable than starting cost segregation today.

How a lookback works

Three steps. No amended returns.

01
Cost segregation study, on a property you already own.
An engineer reclassifies 18–30% of your basis from 27.5/39-year property into 5-, 7-, and 15-year buckets — retroactive to the year you placed it in service.
02
§481(a) adjustment computes the catch-up.
The IRS-blessed math nets every year of accelerated depreciation you should have taken against what you actually took. The difference is your one-year deduction.
03
Form 3115 attaches to this year's return.
DCN 7, automatic consent. One copy with your normal return, one to Ogden. The full catch-up lands in this year's deductions.
Worked examples

Five real properties. Five Year-1 outcomes.

Estimates from the same engine that powers the calculator above. Your numbers will vary based on cost basis allocation and your CPA's review.

Property
Price
Held
Bracket
Catch-up
Year-1 savings
Phoenix duplex
Long-term rental · placed 2021
$500K
4 yrs
32%
$87K
$28K
Nashville STR cabin
Short-term rental · placed 2022
$750K
3 yrs
35%
$158K
$55K
Austin commercial office
Commercial · placed 2020
$1.2M
5 yrs
37%
$230K
$85K
Suburban SFR rental
Single-family · placed 2019
$320K
6 yrs
24%
$42K
$10K
Sedona STR
Short-term rental · placed 2021
$620K
4 yrs
32%
$134K
$43K
Order a study like these See the full math on each example →
Form 3115 vs. amended returns

Why Form 3115 beats amending your prior returns.

Feature
Recommended
Form 3115 §481(a)
Alternative
Form 1040X (Amended)
How many returns to file
1 (current year)
1 per missed year
IRS scrutiny level
Routine
Higher
Years you can claim
All prior years
Last 3 only
Time to file
Weeks
Months per year
Pre-2025 bonus rates
Preserved
Preserved
Net deduction in Year 1
Full back-depr.
Spread across years

Form 3115 is the IRS-blessed way to fix missed depreciation. You file it once, attached to your normal return, and the entire catch-up adjustment lands in this year's tax return. Read the full comparison →

In-depth guides

The mechanics behind the math.

Six guides on how Form 3115 §481(a) actually works, written by the engineering team that runs the calculator.

Filing
Form 3115 for Cost Segregation: A Step-by-Step Filing Guide (2026)
12 min read · Updated 2026
Math
§481(a) Adjustment: How Catch-Up Depreciation Actually Works
10 min read
Decision
Form 3115 vs. Amended Returns: Which Should You Use?
9 min read
Proof
Catch-Up Depreciation Examples: 5 Real Properties, 5 Tax Outcomes
10 min read
Limits
How Far Back Can You Catch Up Missed Depreciation?
8 min read
STR
Catch-Up Depreciation for Short-Term Rentals: The STR Lookback Strategy
10 min read
FAQ

Common questions, answered without fluff.

Catch-up depreciation is the §481(a) adjustment that lets you claim every year of missed accelerated depreciation in a single current-year tax return. It's filed via Form 3115 and doesn't require amending prior returns.
All the way back to the year the property was placed in service. Form 3115 has no 3-year statute-of-limitations cap — that limit only applies to amended returns under Form 1040X.
No. The §481(a) adjustment collapses every year of missed depreciation into the current return. You file Form 3115 once, attached to your regular 1040, and a copy goes to the IRS Ogden service center.
Form 3115 is a change in accounting method — it claims all prior catch-up in the current year. Form 1040X is an amended return — it reopens specific prior years (max 3) and is generally only used when 3115 doesn't apply, e.g. for a sold property.
Typically 2–4 weeks from order to delivered report. Our $495 base study is software-driven, then reviewed by a licensed engineer, with the §481(a) schedule and Form 3115 attachment included.
No. Form 3115 with DCN 7 (the depreciation method change) is an automatic-consent change. The IRS sees thousands of these every year. Audit risk is comparable to filing a normal Schedule E.
That's the most common case. The §481(a) adjustment nets out what you've already claimed (straight-line over 27.5 or 39 years) against what you should have claimed under cost segregation. The difference is your catch-up.
Not via Form 3115. For a property already disposed of, the only path is amending the prior returns (Form 1040X), which limits you to the last 3 years. Catch-up applies to property you still own.
Stop leaving deductions in prior years.
$495
Lookback study. 40+ page IRS-defensible report. Form 3115 attachment included.
Order your study
CPA-ready IRS-defensible RSMeans methodology Refund if your CPA can't use it