Should You Do Cost Segregation the Year You Buy?

Why the purchase year is the path of least resistance

Every reason the purchase year is the cleanest moment to do a study comes down to one thing: nothing needs correcting yet. The closing statement showing what was paid and for what is sitting right there. The appraisal or purchase price allocation separating land value from building value has just been produced. Photographs from the sale listing or an inspection are recent. None of that has to be reconstructed from years-old records or county archives.

• The engineering team classifies the building using records that are days or weeks old, not years old.
• The first depreciation schedule the property ever runs is already the correct one, component by component.
• There is no section 481(a) computation and no Form 3115 involved, because there is no prior, incorrect depreciation to catch up on.

The bonus depreciation timing advantage

Bonus depreciation under section 168(k) is fixed by the property's acquisition date, not by the year the study happens to be performed. Property acquired after January 19, 2025 gets 100% bonus depreciation, restored permanently by the 2025 One Big Beautiful Bill Act, on any 5-, 7-, or 15-year components a study identifies. Property acquired earlier, between 2023 and that date, sits on the phase-down rate that applied in its own acquisition year instead.

Doing the study in the purchase year does not change which rate applies, the acquisition date already fixed that, but it does mean the deduction the rate produces starts flowing on the very first year's return instead of arriving later through a catch-up. For an owner planning cash flow around a new acquisition, that first-year timing can matter as much as the total dollar amount.

What this looks like in real numbers

One recently delivered study on a mid-rise office building, done alongside the purchase, identified $479,220 in first-year increased deductions on a $2,971,345 building basis, against a $12,000 fee, a 39.9 to 1 ratio. Because the study was tied to the purchase year, that $479,220 became part of the very first depreciation schedule filed on the property, not a correction filed years afterward.

First-year deductions on commercial property under current bonus rules typically run about 16 to 21% of building basis, and the share of basis a study shifts into faster schedules typically runs 15 to 35%, with hospitality and restaurant properties running toward the high end and simple industrial shells toward the low end.

When waiting is genuinely fine

None of this means an owner who does not study the property in the purchase year has lost anything permanent. A look-back study reaches the same depreciation, all the way back to the placed-in-service date, and delivers it through a single current-year Form 3115 filing with a section 481(a) catch-up. The mechanics of that path are covered on our already-own guide. The only cost of waiting is the time value of the deduction (a dollar claimed sooner is worth more than the same dollar claimed later) and, if a component gets replaced along the way, the partial asset disposition election on that component, which must be claimed in the year of the replacement itself.

Owners closing on a property in the middle of a busy renovation or lease-up period sometimes reasonably choose to handle the study once things settle, and that choice does not forfeit the depreciation. It just moves the filing mechanism from a first-year schedule to a look-back. Our waiting-costs guide walks through exactly what is and is not affected by that delay.

The same logic applies to new construction

"The year you buy" is really shorthand for "the year the property is placed in service," and cost segregation applies the same way to new construction as it does to a purchase. A building just completed has the same clean-records advantage as one just purchased: the general contractor's cost breakdown is fresh, the certificate of occupancy sets a clear placed-in-service date, and there is no prior depreciation to correct. An owner who built rather than bought is in the same favorable position described throughout this page. See our new construction guide for the specifics of that path.

Purchase-year timing matters less for short-term rentals

The purchase-year advantage described here is largely a commercial-property phenomenon, tied to how much fresher a closing statement or appraisal is right after the transaction. Short-term rental and residential studies work from the listing photos already on Airbnb or VRBO, with no site visit and no owner homework, whether the study happens the week of closing or five years later. An STR owner is not giving up meaningful process simplicity by waiting; the decision there comes down mostly to which filing mechanism, first-year schedule or look-back, fits the owner's broader tax planning for that year.

A practical note for the purchase-year path

If you are planning to study a property in the year you buy it, the fastest path is starting the free Preliminary Benefit Estimate before or right at closing. The estimate models the likely first-year acceleration using the purchase price and property type, no site visit or owner homework required to get that first number, and gives a real target before the engineering work begins.

Because turnaround (generally 4 to 6 weeks during tax season, 2 to 3 weeks in January and February) needs to fit inside the window before the return gets filed, starting the estimate early rather than waiting until closer to the filing deadline gives the engineering team the most room to work with.

Frequently asked questions

Do I need the study finished before I file my first year's tax return?

The engineered report needs to be complete before the CPA finalizes the depreciation schedule on the return that reflects it, which is why turnaround (generally 4 to 6 weeks during tax season, 2 to 3 weeks in January and February) matters for a purchase-year study more than for a look-back.

Does buying at year-end change anything about doing the study in the purchase year?

The engineering itself is the same regardless of when in the year the closing happens. What matters is that the study is completed in time to inform the first depreciation schedule filed for that tax year, so a late-year closing compresses the available turnaround window.

Is a purchase-year study cheaper than a look-back study?

Every study is custom-priced to the property, and the engineering scope is comparable either way since the same components are being classified. Pricing differences between studies come from property size and complexity, not from whether the study happens in the purchase year or later.

What if I already filed my first year's return without a study?

That is exactly the situation a look-back study is built for. The missed depreciation is not lost, it is captured through a Form 3115 filing with a section 481(a) catch-up on a later year's return, with no need to amend the return you already filed.