Start with the depreciation schedule attached to your most recent return. Preparers almost always include a fixed asset detail or depreciation report showing each asset, its placed-in-service date, method, life, prior accumulated depreciation, and the current-year deduction. That claimed-to-date column is the exact input a Form 3115 look-back needs.
Where the numbers live
- Fixed asset or depreciation schedule. The supporting report from your preparer or tax software. Not an official IRS form, but the most complete record. Ask prior preparers for it; they generally retain it.
- Form 4562. Filed with the return for any year you placed assets in service. It shows that year's depreciation by category but not a running lifetime total, so you may need several years of them.
- Schedule E, line 18. The depreciation deduction claimed each year per property. Summing line 18 across your ownership years approximates total claimed, though it mixes building, improvements, and appliances together.
- IRS transcripts. A return transcript reproduces return line items, which can backstop missing Schedule E totals, but it will not reconstruct asset-level detail.
Why the number matters
The section 481(a) catch-up on Form 3115 is defined as allowable minus claimed, so an inaccurate claimed figure flows straight into a wrong deduction. It also controls basis: under IRC section 1016(a)(2), basis is reduced by depreciation allowed or allowable, whichever is greater, so your gain and unrecaptured section 1250 amount at sale depend on this history even for years you skipped the deduction. The IRS Cost Segregation Audit Techniques Guide tells examiners to tie the 481(a) computation back to exactly these records.
Worked example
An owner bought a rental in 2020 for $650,000 with $130,000 allocated to land, so the expected straight-line deduction on the $520,000 building is about $18,900 per year under the 27.5-year table in IRS Pub 946. Schedule E line 18 shows only $14,500 per year because the original preparer set the asset up with too much land. Six years in, claimed depreciation is $87,000 versus roughly $112,000 allowable. That gap is itself fixable through the same Form 3115 process, and the corrected claimed-to-date figure then feeds the cost segregation catch-up math.
When the records are gone
If prior preparers are unreachable and software files are lost, the schedule can be rebuilt from the closing statement (cost and land allocation), each year's Schedule E line 18, and any Form 4562s you can locate. What you cannot do is ignore the history: section 1016(a)(2) reduces basis whether or not you find the paperwork.
Amadae's property tracking tab holds each property's basis, land allocation, and depreciation history, and its Form 3115 workflow consumes those claimed-to-date numbers directly when a look-back study is on the table.