Most of the paperwork a cost segregation study needs is already sitting in your closing folder and your tax file. The engineering firm is reconstructing how your purchase price breaks down into 5, 7, and 15 year personal property and land improvements versus 27.5 or 39 year building, so everything it asks for ties back to cost basis and physical detail.
The core document set
The settlement statement establishes total cost basis, including capitalized closing costs, under the basis rules in IRS Publication 946. The purchase contract confirms what was actually acquired, which matters when a deal includes furniture or equipment. An appraisal or the county assessor card supports the land allocation, since land is never depreciable under Publication 946. If the property is already on a filed return, the depreciation schedule behind Form 4562 shows what has been claimed so far, which drives the section 481(a) catch-up if the study is a look-back filed through Form 3115. Renovation invoices, permits, and contractor payment records let the firm use actual costs instead of estimates, which the IRS Cost Segregation Audit Techniques Guide treats as the strongest support. Floor plans, site plans, and a current photo set document the components being classified.
A worked example
Say you bought a $750,000 duplex in 2024 and renovated the kitchens for $60,000 in 2025. The settlement statement fixes the $750,000 basis, the assessor card supports a 20% land allocation of $150,000, the kitchen invoices support reclassifying cabinetry and appliance hookups directly from actual cost, and your 2024 depreciation schedule tells the preparer exactly how much straight-line depreciation the section 481(a) adjustment must true up on Form 3115.
What happens if something is missing
Missing documents rarely kill a study, but they slow it down and weaken it. Without renovation invoices the engineer must estimate component costs from industry data, which is acceptable under the Audit Techniques Guide but easier for an examiner to challenge. Without a prior depreciation schedule, a look-back cannot be computed at all until the history is reconstructed from old returns or a transcript.
Where Amadae fits
Amadae's cost segregation screen needs only the address, purchase price, and property type to model the likely reclassification and first-year benefit. It is a screening estimate, not an engineering study. If the numbers justify going forward, Amadae coordinates the document handoff to an independent engineering firm, prepares the Form 3115 and section 481(a) catch-up math when a look-back applies, and files the return that uses the study. Gather the checklist below before the engagement starts and the whole chain moves faster.