Here’s a story that plays out a lot. Someone owns a rental for eight years. They’ve been claiming “some depreciation,” or no depreciation, or the wrong depreciation. They realize it and panic about amending eight years of returns. Good news: you don’t amend. You file a Form 3115.
What it’s used for
- Missed depreciation on a rental or business asset, going back years.
- Cost segregation catch-up on a building placed in service in a prior year. You can re-allocate the basis into 5/7/15-year buckets retroactively and claim the missed accelerated depreciation now.
- Switching to the tangible property safe harbors (routine maintenance, repairs vs. improvements treatment) if you historically capitalized work that should have been deducted.
- Correcting recovery periods (e.g., 39-year for what should be 15-year land improvements).
The math: a quick example
You bought a $600,000 rental five years ago. You correctly depreciated the building (about $14,500 per year), but you never did a cost seg. A cost seg study shows that $150,000 should have been in the 5- and 7-year buckets, with bonus depreciation, taking the front-loaded depreciation way up. The cumulative under-depreciation across five years is, say, $100,000. Form 3115 with a § 481(a) adjustment lets you claim that whole $100,000 as a deduction on this year’s return. At a 37% bracket, that’s $37,000 in tax savings, in the current year, without amending anything.
It is generally automatic, not discretionary
For most situations (missed depreciation, cost seg catch-up, tangible property elections), the IRS provides “automatic consent.” You file Form 3115 with the return, the IRS doesn’t need to approve it case-by-case, and the change is effective. The list of qualifying changes is updated periodically (currently Rev. Proc. 2024-23).
Some changes still require a private letter ruling and an actual review. Your tax pro will know which bucket applies.
Two copies, two deadlines
One copy of Form 3115 is attached to your timely-filed return for the year of change (with extensions). A second copy is mailed to the IRS in Ogden, Utah. Both have to happen for the election to be valid. Missed one? There is some relief under § 301.9100, but it is discretionary.
The § 481(a) catch-up
The cumulative difference between depreciation actually taken and depreciation that should have been taken is the § 481(a) adjustment. A negative adjustment (you under-depreciated) is taken in full in the year of change, accelerating the deduction. A positive adjustment (you over-depreciated, rare) is spread over four years. Negative is what 99% of cases are.
What it doesn’t do
Form 3115 is for method changes, not for fixing errors on a specific year’s return that aren’t method issues. Miscalculated the gain on a sale? That’s an amendment, not a 3115. Missed a deduction that wasn’t depreciation-related? Probably an amendment too.