Form 3115: How to Catch Up on Missed Rental Depreciation

TL;DR: If you've owned rental property for two or more years and never claimed depreciation (or claimed the wrong amount), Form 3115 lets you fix it by taking the entire missed deduction as a single adjustment on this year's return, no amended returns required. It's filed as a "change in accounting method," and depreciation you were entitled to but never claimed still reduces your cost basis whether you deducted it or not — so fixing it usually saves you money at tax time.

_Last reviewed: August 2026 · 8 min read_

Some landlords go years without realizing they never claimed depreciation on their rental, or claimed it on the wrong basis, or missed it entirely on an addition or a big appliance purchase. The fix isn't always to amend every open year one by one. In many cases, Form 3115 lets you correct the whole history in one move.

Okoniq Property Hub keeps a running record of what you've depreciated, when, and on what basis, so a gap like this shows up long before it turns into a bigger cleanup project.

What is Form 3115 and why would a landlord need it?

Form 3115, "Application for Change in Accounting Method," is the IRS form you file to change how you've been treating an item on your tax return, including how you've been depreciating (or not depreciating) a rental property. The IRS treats "no depreciation" and "wrong depreciation" as an accounting method, not a one-off error, which is why the fix runs through a method change rather than a simple correction.

This matters because of a rule that trips up a lot of owner-operators: depreciation is allowed or allowable whether you actually claimed it or not. If you were entitled to a deduction and skipped it, the IRS still treats your cost basis as if you'd taken it. That means when you eventually sell, your gain (and any depreciation recapture) is calculated using the depreciation you should have claimed, not what you actually deducted. Form 3115 exists so you can claim the deduction you're owed instead of just eating the basis reduction with nothing to show for it.

How does the catch-up adjustment actually work?

The mechanism is called a §481(a) adjustment, and it lets you take the entire missed depreciation from all prior years as one deduction on the current year's return. You don't need to amend every past tax year individually. Instead, you calculate what depreciation you should have claimed since you placed the property in service, subtract what you actually claimed, and the difference becomes a single negative §481(a) adjustment, which flows through as a deduction on this year's Schedule E.

This is different from correcting a math error or a missed line item, which usually gets handled through an amended return for a missed rental deduction. Amended returns generally have a limited window tied to when you filed, so they work for a recent, isolated mistake. Form 3115 doesn't have that same lookback limitation on the catch-up amount — it's built specifically for situations where the error has been compounding for years.

Form 3115 or an amended return — which one actually fixes your situation?

The right tool depends on how long the depreciation has been missing and how many years are involved.

| | Form 3115 (method change) | Amended return | |---|---|---| | Best for | Depreciation missed for 2+ tax years | A single recent year's error | | How it's claimed | One catch-up deduction, current year | Refiled deduction on that specific prior year | | Lookback window | Not limited the same way | Generally limited — see your CPA | | Filing complexity | Higher — a formal method-change application | Lower — a straightforward refile | | Common trigger | Never claimed depreciation at all, or used the wrong basis/method for years | One missed receipt, one skipped repair deduction |

If you only missed depreciation on last year's return, an amended return is usually simpler. If you've owned the property for several years and never claimed depreciation at all, or you've been depreciating land value by mistake, or you missed a big renovation, Form 3115 is typically the more efficient path because it consolidates everything into one adjustment instead of multiple amended filings.

What's the process for actually filing Form 3115?

You file Form 3115 with your current-year tax return, attaching it to describe the accounting method you're changing from and to, along with the calculation supporting your §481(a) adjustment. This is where records matter most: you need to reconstruct the property's placed-in-service date, its original cost basis, land-versus-building allocation, and any capital improvements added along the way.

The IRS's automatic change procedures cover most routine depreciation corrections, meaning many landlords can make this change without a formal ruling request, but the paperwork still needs to be exact. A property's recovery period is set by statute, and it hasn't been the subject of recent legislative change the way bonus depreciation and casualty losses have — confirm the current figure on IRS.gov or with a CPA before you calculate the catch-up amount, since getting the recovery period wrong throws off every year's number in the adjustment.

If a cost segregation study is part of the picture — say you're separating out 5-year appliances from the building itself — that study needs to happen before you finalize the Form 3115 numbers, not after.

What if the missed depreciation involves bonus depreciation or a recent purchase?

Bonus depreciation rules changed significantly and it's worth checking which version applies to your purchase. For qualified property acquired after January 19, 2025, the One Big Beautiful Bill made 100% first-year bonus depreciation permanent, reversing the phase-down that used to apply. Taxpayers can instead elect 40% under interim guidance (Notice 2026-11) if that suits their situation better. If the missed depreciation involves an appliance, HVAC system, or similar 5-year property bought around that window, see how bonus depreciation actually works now before you file, because it changes the catch-up math substantially.

Smaller missed items sometimes don't need Form 3115 at all. If what slipped through was a $1,800 water heater or a $900 refrigerator, the $2,500 de minimis safe harbor may let you expense it outright in the year it's caught, rather than folding it into a multi-year depreciation catch-up. It's worth sorting your missed items into "big, structural, multi-year" versus "small, expensible" before deciding how much of this needs Form 3115 versus a simpler fix.

FAQ

Do I need a CPA to file Form 3115?

It's strongly recommended. The §481(a) calculation requires reconstructing years of basis and depreciation history accurately, and a mistake compounds across every year included in the catch-up, so most landlords use a CPA or enrolled agent for this specific form.

Does filing Form 3115 trigger an IRS audit?

Filing the form itself isn't a red flag — it's a standard, IRS-sanctioned process for correcting depreciation, and thousands of these are filed automatically every year. What matters is that your supporting math (basis, placed-in-service date, land allocation) is documented and consistent.

Can I use Form 3115 if I only missed depreciation on one recent tax year?

You can, but an amended return is usually simpler and faster for a single recent year. Form 3115 earns its complexity when the missed depreciation spans multiple years or you never started depreciating the property at all.

What happens to my basis if I never fix missed depreciation?

Your basis is reduced by the depreciation you were allowed to claim, whether you claimed it or not. Skipping the fix means you lose the deduction now but still face the same reduced basis, and higher taxable gain, when you eventually sell.

Does missed depreciation affect what I owe when I sell the property?

Yes. Depreciation recapture at sale is calculated on the depreciation you were entitled to take, not just what you actually deducted, so unclaimed depreciation can mean paying recapture tax on a deduction you never benefited from. See what happens at sale for how that calculation works.

<div class="glass rounded-2xl p-5 mt-7 max-w-4xl border border-red-400/30 bg-red-500/5"> <div class="flex items-start gap-3"> <span class="text-2xl flex-shrink-0">⚠️</span> <div class="flex-1 min-w-0"> <p class="text-red-200 text-sm font-bold">Not tax advice</p> <p class="text-slate-300 text-xs mt-1 leading-relaxed"> This post assumes a landlord who has missed depreciation on a rental property for two or more tax years and explains the general mechanics of Form 3115. It does not account for your specific tax bracket, entity structure, state tax treatment, prior audit history, or any legislation passed after July 2026. Tax rules change and depend on your specific situation. Talk to a licensed CPA before acting on anything here, and confirm current figures on IRS.gov. </p> </div> </div> </div>