Cost Segregation and 1031 Exchange Strategy on Large Deals

The study does not break the exchange: classification for depreciation and for §1031 are separate questions

This is the first thing to settle, because it is the thing most often stated wrongly. Reg. §1.1031(a)-3 defines real property by what an item is — land, an inherently permanent structure, a structural component — and says a structure or portion of a structure "may be section 1245 property for depreciation purposes" while still being real property under the section.

So carving a building into 5-, 7- and 15-year lives does not turn part of your relinquished property into disqualified personal property. The whole building can go into the exchange.

The consequence is narrower and easier to miss: the deferral of ordinary-income recapture is governed by §1245 and its own regulation, and that rule was written for equipment swaps, not for cost-segregated real estate.

§1245(b)(4) measures your deferral against the §1245 content of what you buy, not against the cash you keep

§1245(b)(4) limits the ordinary income taken into account on a §1031 disposition to the sum of the gain recognized plus "the fair market value of property acquired which is not section 1245 property." Reg. §1.1245-4(d) restates that and adds the mechanics.

Paragraph (d)(4) does the work when one transaction disposes of both kinds of property. The amount realized is allocated between the §1245 and non-§1245 assets by relative fair market value; the §1245 share is then deemed to have bought the §1245 property acquired first, and only what is left over is treated as buying non-§1245 property.

Read backwards, that is a planning instruction. Match the §1245 content of the replacement to the §1245 content of what you are selling, and the cap never binds. Fall short, and the shortfall is ordinary income in the year of the exchange.

Worked example: $2,000,000 carved out, $200,000 bought back, $800,000 of ordinary income and no cash

Hypothetical with round numbers. A study on a $10,000,000 property moved $2,000,000 of cost into 5- and 7-year §1245 assets, all of it expensed, so those components carry a zero adjusted basis and a $2,000,000 recomputed basis. The property now sells for $10,000,000, and at that date the §1245 components are worth $1,000,000 of the price.

The replacement also costs $10,000,000, but it is a newer, land-heavy asset with only $200,000 of §1245 content. Allocate first: $1,000,000 of the amount realized belongs to the §1245 assets, and §1245(a)(1) would treat all $1,000,000 as ordinary income, since the recomputed basis is higher and the adjusted basis is zero.

Now apply the cap. No boot is taken, so the gain recognized is zero. Of the $1,000,000 deemed realized on the §1245 assets, $200,000 is matched against the §1245 property acquired and $800,000 is treated as spent on non-§1245 property. The ordinary income taken into account is therefore $800,000 — roughly $296,000 of federal tax at a 37% marginal rate, on a deal that produced no cash to pay it. Have your CPA run your own allocation before you sign anything.

Site work usually rides along; the short-life bucket has teeth, and §168(n) has just added a new one

Not every accelerated component is §1245 property. Parking lots, curbs, site utilities and landscaping at an apartment or retail property are land improvements depreciated over 15 years, but they remain real property outside the §1245 definition, so they carry forward in the exchange rather than triggering the cap.

The Instructions for Form 4797 set out the §1245 categories that matter here: depreciable personal property, and tangible real property other than buildings and their structural components that is used as an integral part of manufacturing, production, extraction or the furnishing of utilities. That second category is why industrial sellers see much larger §1245 buckets than multifamily sellers do.

Publication 544 flags the newest wrinkle: §1245 property now includes qualified production property where the taxpayer designates and elects it under §168(n). Electing that on a manufacturing building converts an entire structure into §1245 property, which is an enormous first-year deduction and an equally large obstacle to a clean exchange later.

• 5- and 7-year interior components: §1245, and the bucket the cap is aimed at.
• 15-year land improvements at a non-industrial property: §1250 real property, carried forward.
• Tangible real property integral to manufacturing: §1245 under §1245(a)(3)(B).
• Qualified production property elected under §168(n): §1245, per Publication 544.

On the replacement, only the excess basis is new depreciable money — and that is where 100% bonus lives

Reg. §1.168(i)-6 splits the replacement's basis in two. The exchanged basis is the lesser of the replacement's basis or the relinquished property's adjusted depreciable basis, and it keeps depreciating on the relinquished property's remaining recovery period, method and convention. Everything above it is excess basis, "treated as property that is placed in service by the acquiring taxpayer in the year of replacement."

A cost-segregation study on the replacement therefore reclassifies the excess basis, not the whole purchase price, unless you make the election in Reg. §1.168(i)-6(i) on a timely filed original return, which treats the sum of both layers as placed in service at replacement.

The size of that excess basis is the real variable. Hypothetically, relinquishing a property with a $2,000,000 adjusted basis and buying a $10,000,000 replacement leaves $8,000,000 of excess basis; a study that assigns 25% of it to property with a recovery period of 20 years or less produces $2,000,000 of eligible cost, and Publication 946 confirms that P.L. 119-21 reinstated the 100% special depreciation allowance for qualified property acquired and placed in service after January 19, 2025.

Four sequencing decisions, and the last safe date for each

Reporting follows the same path every year: ordinary income from the exchange appears on Form 8824 line 21 and carries to Form 4797. Confirm the whole sequence with your CPA and, where an election is involved, with your attorney, because none of it can be fixed after the closing.

• Before the study: if an exchange is likely within a few years, model the §1245 bucket you are creating against the kind of replacement you would realistically buy. A study that maximizes year-one deduction can create an ordinary-income liability you cannot pay with exchange proceeds.
• Before the listing: get the relinquished property's §1245 components valued at current fair market value, not at original cost. The allocation in Reg. §1.1245-4(d)(4) runs on fair market value, and a defensible appraisal is what keeps that number honest.
• Before day 45: ask each candidate replacement for a purchase-price allocation or a preliminary study, so you know its §1245 content while you can still identify something else.
• Before the return is filed: decide whether to elect out of the additional first-year allowance, and whether to make the Reg. §1.168(i)-6(i) election. Publication 946 notes that a taxpayer may elect a lower allowance, and both choices are made on a timely filed return.