How to Correct Prior Year Depreciation Errors

To correct prior year depreciation errors, you generally file IRS Form 3115, Application for Change in Accounting Method, and take a single Section 481(a) adjustment in the current year instead of amending each old return. The reason to act rather than let the mistake sit is Section 1016(a)(2): when you sell the asset, the IRS reduces your basis by the greater of the depreciation you actually claimed or the depreciation you were entitled to claim.¹ Miss the deduction and you still lose the basis. Fixing the error is how you recover deductions that would otherwise be gone for good.

Amended Return or Form 3115?

Not every depreciation mistake needs Form 3115. If the error sits in a single recent year and the refund window is still open, you can file Form 1040-X (or the equivalent for your entity). You generally have three years from the date you filed the original return, or two years from the date you paid the tax, whichever is later.²

Once the same impermissible depreciation treatment appears on two or more consecutively filed returns, the IRS treats it as an established accounting method.³ At that point, correcting it is a formal change in accounting method, and Form 3115 is the required path.⁴

The practical appeal of Form 3115 is that it reaches into closed years. Even if the statute of limitations expired on returns from a decade ago, the Section 481(a) adjustment captures the cumulative effect of every prior year’s error and pulls it into the current return. You never amend the old filings.

Pull Your Asset Records First

Before you touch the form, you need the following for each asset with an error:

Original cost or unadjusted basis, including capitalized costs like sales tax, delivery, and installation.
Date placed in service, which controls the recovery period start and the first-year convention.
Asset class and recovery period. Computers and peripherals, for example, use a five-year recovery period; office furniture uses seven. The classification tables are in IRS Publication 946.⁵
Depreciation method you should have used: 200% declining balance, 150% declining balance, or straight-line.
Depreciation actually claimed on every prior-year return.
Any Section 179 expense or bonus depreciation taken in the first year, which reduces the depreciable basis before MACRS begins.

Most corrections stall here. If you cannot reconstruct what you claimed against what you should have claimed, the Section 481(a) math will not come out right. Find the old returns and depreciation schedules before you fill out anything.

Calculating the Section 481(a) Adjustment

The Section 481(a) adjustment is one number that captures the whole cumulative error. It equals the total depreciation that should have been claimed through the end of the year before the year of change, minus the total depreciation actually claimed over the same period.⁶

A simplified example. You bought equipment for $50,000 in 2020 with a seven-year MACRS recovery period, but you depreciated it over ten years on your returns. By the beginning of 2026, you should have claimed roughly $43,500 under the correct seven-year schedule. If you actually claimed only $35,000 using the wrong schedule, your Section 481(a) adjustment is negative $8,500. That $8,500 represents deductions you were entitled to but never took.

The sign of the adjustment determines how it hits your return.

Negative Adjustment: You Under-Depreciated

A negative adjustment means you claimed less than you should have. The IRS lets you take the entire negative adjustment as a deduction in the year of change. For a taxpayer who never depreciated an asset at all, this can produce a substantial one-time write-off.

Positive Adjustment: You Over-Depreciated

A positive adjustment means you claimed more than you were entitled to, so the correction increases taxable income. The IRS generally lets you spread that income inclusion evenly over four tax years, starting with the year of change, instead of absorbing it all at once.

One detail that trips people up: use the correct convention for when the asset was placed in service. Most personal property uses the half-year convention, but if more than 40% of the year’s depreciable property was placed in service in the last quarter, the mid-quarter convention applies instead. The wrong convention throws off every year of the calculation.

Filing Under Automatic Consent

Most depreciation corrections qualify for the automatic consent procedure. You do not request permission in advance and you do not pay a user fee. You file the form with your return, and consent is presumed unless the IRS later says otherwise.⁷

To qualify, you need to:

Enter the correct Designated Change Number (DCN) for your type of depreciation error. Depreciation and amortization changes are covered under Section 6 of the list of automatic changes in Revenue Procedure 2025-23.⁸
Not be under IRS examination on the asset or depreciation issue you want to change.
Meet the scope limitations and certify the required representations, including that the change does not involve a partnership item under the centralized audit regime.
Check the automatic change box on the form rather than filing it as a request for advance consent.

The form also requires a detailed statement describing the asset, the incorrect method you were using, the correct method you are adopting, and the authority for the change. Cite the specific Internal Revenue Code sections and the governing revenue procedure.

Common depreciation errors that fit automatic consent include using the wrong recovery period, using the wrong method (straight-line instead of 200% declining balance, for instance), failing to claim any depreciation on a qualifying asset, and applying the wrong convention. Qualified small taxpayers may be eligible for a reduced filing requirement on certain DCNs, completing only specific lines and schedules instead of the entire 10-page form.⁷ Check that before filling out everything.

Don’t Forget the Second Copy

Form 3115 has a filing step that catches a lot of taxpayers off guard: you must submit two copies, and missing either one can invalidate the automatic consent.

The first copy attaches to your timely filed federal income tax return for the year of change. That is the return where the Section 481(a) adjustment actually hits your income. If you extended, the form is due by the extended deadline.⁷

The second copy goes separately to the IRS in Ogden, Utah. It must be postmarked no later than the day you file the tax return. The address is Internal Revenue Service, Ogden, UT 84201, Attn: CC:ITA. Keep the certified mail receipt. The IRS does not send a confirmation letter for automatic changes, so that receipt is your only proof of compliance if the issue comes up later.

When Automatic Consent Isn’t Available

If your situation falls outside the automatic consent scope, Form 3115 becomes a non-automatic change. You file before the end of the tax year you want the change to take effect, pay a user fee, and wait for written IRS approval before implementing it.

The most common reason taxpayers get pushed into the non-automatic track is that the depreciation issue is already under IRS examination. Other disqualifying factors include being under audit for the year of change and failing to meet the specific eligibility conditions listed in the revenue procedure for your DCN. If you are not sure whether you qualify, paying a CPA familiar with Form 3115 is usually worth it. Fees typically run a few hundred dollars for a straightforward preparation and climb for complex multi-asset corrections.

Bonus Depreciation and Section 179 Make It Messier

If the asset qualified for bonus depreciation or a Section 179 expense deduction, the correction has more layers. Both reduce the depreciable basis before regular MACRS begins, so an error in the placed-in-service year cascades into every subsequent year’s calculation.

For 2026, the One Big Beautiful Bill Act restored 100% first-year bonus depreciation for eligible business property acquired after January 19, 2025. If you placed qualifying property in service during the prior phase-down period (2023 through early 2025) and did not claim the correct reduced bonus percentage, your Section 481(a) adjustment has to account for the bonus shortfall along with any MACRS errors it set off.

Section 179 has its own annual dollar limits and taxable income restrictions that change each year. Verify the limit that applied in the year you placed the asset in service. An incorrect Section 179 amount ripples through every subsequent year of MACRS depreciation on the remaining basis, and that ripple is part of what Form 3115 is correcting.

1
Office of the Law Revision Counsel. 26 U.S. Code 1016 – Adjustments to Basis
2
Internal Revenue Service. File an Amended Return
3
Internal Revenue Service. Revenue Procedure 2004-11
4
Internal Revenue Service. About Form 3115, Application for Change in Accounting Method
5
Internal Revenue Service. Publication 946 How To Depreciate Property
6
Internal Revenue Service. IRC 481(a) Adjustments for IRC 263A Accounting Method Changes
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Internal Revenue Service. Instructions for Form 3115 – Application for Change in Accounting Method
8
Internal Revenue Service. Revenue Procedure 2025-23 – List of Automatic Changes