The Partial Disposition Election: How to Deduct the Old Roof the Year You Replace It.

A landlord replaces the roof on a duplex after a hailstorm: $28,000 to the roofer, plus $3,500 to tear off and haul away the old shingles. The new roof goes on the depreciation schedule at 27.5 years, and most returns stop there. But the old roof is still sitting inside the building's basis, and left alone it will keep depreciating, a roof in a landfill, deducted a sliver at a time through 2043. The partial disposition election turns the roof replacement into a current deduction instead: write off the old roof's entire remaining basis this year, on this year's return, and deduct the tear-off costs with it.

MACRS treats a building and its structural components as a single asset, which is why the old roof has no line of its own on your depreciation schedule. Before 2014 that was the end of the story: you capitalized the new roof and depreciated two roofs at once, one of them in a dumpster. The 2014 final regulations, T.D. 9689, changed that by letting you elect to treat the retirement of a portion of an asset as its own disposition. You carve the old roof out of the building, compute its remaining basis, and claim the loss on Form 4797. It is a §1231 loss, so if your §1231 results for the year net to a loss, it is ordinary, not capital. The election is annual, per component, and entirely yours: nothing forces you to make it, and nothing but the calendar stops you.

The obvious objection is that your closing statement says what you paid for the duplex, not what you paid for its roof. The regulation anticipates this. Treas. Reg. §1.168(i)-8(f)(3) allows any reasonable method for determining the disposed component's basis and names three: discounting the cost of the replacement back to the year you placed the building in service using the Producer Price Index for Final Demand, a pro rata allocation based on the component's share of the building's cost, or a cost segregation study. The PPI rollback is the workhorse, with one condition built into the regulation: it is only reasonable when the replacement is a restoration rather than a betterment or an adaptation. A like-for-like shingle roof qualifies. If you upgraded to standing-seam metal, discounting the metal price overstates what the original shingle roof cost, so the estimate has to start from a comparable replacement instead.

There is no form and no election statement. Under §1.168(i)-8(d)(2), you make the election by doing it: reporting the gain or loss on your timely filed original return, including extensions, for the year the component was disposed of. That simplicity is the trap. An election you make by filing is an election you miss by filing without it, and the regulation does not allow a do-over on an amended return once the deadline passes. The fallbacks are narrow: an automatic six-month window under Treas. Reg. §301.9100-2 if you filed on time, and after that a private letter ruling under §301.9100-3, with a user fee and no guarantee. The IRS takes the election seriously enough to publish an LB&I practice unit training examiners on how to verify one, which tells you two things: the election is routine, and the workpapers behind the basis estimate should exist before the return does. For a roof replaced in 2026, that means the loss goes on the return due April 15, 2027, or October 15 with an extension.

The current deduction is only half the value. Every dollar of depreciation you claim on a building comes back at sale as unrecaptured §1250 gain, taxed at up to 25%. Keep depreciating a roof that no longer exists and you are manufacturing future 25%-rate gain in exchange for deductions you could have taken as a single loss today. The election removes the old roof's basis and its accumulated depreciation from the building's ledger, so you stop double-depreciating and shrink the recapture waiting at the exit. It is the same discipline that makes cost segregation worth running for high-income landlords, applied at the moment a component leaves the building. And if the property might ever become your home, trimming the depreciation account now also trims the gain that follows the property into a §121 exclusion later. One honest caveat: for a landlord whose rental is a passive activity, the disposition loss lands in the passive bucket under §469, usable against passive income or the $25,000 active-participation allowance rather than wages, until the property is fully disposed of.