A cost segregation study splits a property into the parts that wear out at different speeds, so the shorter-lived ones can be depreciated over their own life instead of the building’s 27½ years. It is ordinary tax practice and it has been for decades.
It has also, for most of that time, been out of reach for anybody with a single rental house. A traditional study means an engineering firm, a site visit and a bill that only makes sense against a commercial building.
What replaced the site visit is a video you take yourself. You walk through your own property with your phone, and software reads what is in it and prices each item against a published construction cost book. You confirm what it found. Your accountant gets the schedules.
A model is allowed to propose and never to decide. Past the point where you confirm something, no model touches the number again.
We are not accountants, engineers or appraisers. Nobody here visits your property or reviews your study by hand, and we do not represent anyone before the IRS.