You Can't Defer Bonus Depreciation. But You Can Choose When It Shows Up.
A late-year rental purchase, a cost segregation study, and Form 3115 — and why the order matters.
A question we hear every fall: "We're closing on a rental property in November. Can we save the bonus depreciation for next year, when we'll actually have income to use it against?"
The short answer is no. The longer answer is that there is a well-established, IRS-sanctioned route that gets you to the same place — and, done right, it lets you drop the entire deduction into whichever future year needs it most.
Bonus depreciation is not a timing election
First, the ground rules. Bonus depreciation applies in the year an asset is placed in service. There is no election to take it a year later. The only election the Code gives you is to opt out, by asset class, on a timely filed return — and if you opt out, that bonus is gone for good. Those assets just run on the regular depreciation schedule.
Two more facts that shape everything below:
The building itself never gets bonus depreciation. Residential rental property depreciates over 27.5 years; commercial over 39. Bonus applies only to the components a cost segregation study carves out — 5-, 7-, and 15-year property such as carpeting, appliances, cabinetry, dedicated electrical, site paving, fencing, and landscaping, plus qualified improvement property in nonresidential buildings.
Under the One Big Beautiful Bill Act, 100% bonus depreciation is permanent for property acquired after January 19, 2025. There is no phase-down clock. Waiting costs you nothing on the rate.
The mechanism: depreciate the building now, do the cost seg later
Here is the sequence.
Purchase year. Depreciate the entire purchase price (less land) as building — 27.5 or 39 years, mid-month convention. Don't do a cost segregation study yet. Critically, do not attach an election out of bonus depreciation for any asset class. Filing quietly is the whole point.
The year you want the deduction. Commission the cost segregation study, dated as of the original placed-in-service date. File Form 3115 (change in accounting method) with that year's return. This is an automatic change — no IRS consent letter needed — under the "impermissible to permissible depreciation method" category.
The catch-up. Form 3115 produces what's called a §481(a) adjustment: the difference between what you actually deducted and what you would have deducted had the components been classified correctly from day one. Because bonus depreciation was the default (you never elected out), "correctly from day one" includes 100% bonus on every qualifying component. A negative §481(a) adjustment is deducted in full, in the year of change.
In plain terms: you never "deferred" bonus depreciation. You simply didn't discover the components until later, and the tax law lets you catch up all at once in the year you discover them.
A worked example
The Nguyens buy an eight-unit building
Mr. and Mrs. Nguyen (married filing jointly, California residents) close on an eight-unit apartment building on November 15, 2026. Mrs. Nguyen manages the family's rentals full-time and qualifies as a real estate professional. They already plan to sell an older duplex in 2027, expecting a gain of roughly $900,000, with no 1031 exchange.
Purchase price | $3,600,000 |
Land (not depreciable) | $900,000 |
Depreciable basis | $2,700,000 |
Reclassified by cost seg to 5/7/15-year (25%) | $675,000 |
Remaining 27.5-year building | $2,025,000 |
2026 return: building-only depreciation. $2,700,000 ÷ 27.5 years × 1.5 months = about $12,300. No cost seg, no bonus election-out.
2027 return: cost seg study completed, Form 3115 attached. The §481(a) catch-up is $675,000 of bonus less the roughly $3,000 of 27.5-year depreciation already claimed on those components — about $672,000, deducted in 2027.
Had they done the cost seg immediately, the $675,000 would have landed in 2026 — a year with six weeks of rental income to absorb it. Instead it lands in 2027, alongside the duplex sale.
Figure 1. Same property, same total depreciation over time. The only difference is which year the $672,000 component deduction lands in. Figures rounded; 2027 under the 3115 approach includes the catch-up plus ordinary building depreciation.
Why the year matters: three gates the deduction has to pass
Landing a large deduction in the right year only helps if the deduction is actually usable that year. Three rules decide that.
1. The passive activity rules (§469)
The catch-up is a rental loss. Unless the taxpayer is a real estate professional who materially participates in the rental (or runs a qualifying short-term rental), a rental loss is passive and can only offset passive income. A stock sale, a business sale, or a spouse's W-2 won't be touched — the loss just sits in suspension until there's passive income or a disposition. For the Nguyens, Mrs. Nguyen's professional status is what makes the 2027 deduction non-passive, so it can offset the duplex gain. Her hours log for 2027 is the document that will matter in an audit, not the cost seg report.
2. The excess business loss limit (§461(l))
Net business losses for a non-corporate taxpayer are capped each year — $256,000 single / $512,000 married filing jointly for 2026, indexed thereafter (expect roughly $524,000 joint in 2027). Anything above the cap becomes a net operating loss carried to the following year. Rental losses from a real estate professional count as business losses.
The subtle part is what counts as business income against that loss. Gain from selling a rental property is §1231 gain from a trade or business, so it goes inside the calculation and absorbs the loss before the cap is ever reached. Gain from selling stock, crypto, or another investment asset does not. Same deduction, very different result:
Figure 2. With a rental sale, the §1231 gain sits inside the business-loss computation and the whole catch-up is used. With a stock gain, only $40,000 of rental income plus the ~$524,000 cap is usable in 2027; the remaining ~$108,000 carries to 2028. Cap figure for 2027 is an estimate.
3. Rate arithmetic and the 3.8% net investment income tax
The catch-up is an ordinary deduction. It offsets ordinary income (wages, net rents) first, at up to 37%; only what's left reaches the capital gain at 20% (or 25% for unrecaptured depreciation). That still saves real money, but it's worth knowing the deduction is worth less against gain than against salary — and that later recapture on the new property comes back at ordinary rates.
On NIIT, there's a counterintuitive wrinkle: if the real estate professional also meets the 500-hour safe harbor, the rental is a non-investment trade or business, and its loss doesn't reduce net investment income — so the 3.8% on the gain is untouched. Worth modeling before the year of change.
For the Nguyens — real estate professional, §1231 gain, joint filers — all three gates open. Offsetting roughly $190,000 of ordinary income and about $480,000 of the duplex gain, the 2027 federal savings is on the order of $140,000 to $150,000. Illustrative and rounded, but that's the shape of it.
The California footnote
California does not conform to bonus depreciation, caps §179 expensing at $25,000, and treats qualified improvement property as 39-year. So the California version of the Form 3115 catch-up contains no bonus at all — only the benefit of moving components from 27.5-year to their shorter regular lives. For a fourth-quarter purchase that's further shrunk by the mid-quarter convention.
Figure 3. Federal catch-up includes 100% bonus on the components. California's reflects only one year of accelerated regular depreciation (5-, 7-, and 15-year MACRS, mid-quarter convention) less the 27.5-year amount already claimed. The remaining California basis depreciates over the shorter lives in later years.
The California deduction is small, but it does offset gain taxed at ordinary rates of up to 13.3%, and California has no excess-business-loss cap and no preferential capital gains rate. Treat it as a modest bonus, not the reason to do the planning.
How far out can you push it?
Further than most people expect. There is no statute of limitations on the year of change for a depreciation method change. A cost seg done three or five years after purchase, with Form 3115 filed for that year, still catches up everything back to the placed-in-service date — including 100% bonus, which locks in at the acquisition date. The taxpayer gets to pick the year.
The conditions that have to hold:
Still own the property in the year of change. The year of sale is the last chance; after that, only amended returns within the normal statute can fix it.
Don't amend the purchase year to claim the cost seg. Amending uses up the change and leaves nothing to carry forward. (For depreciation there's a special rule allowing Form 3115 as early as the second year, so filing the 3115 with the very next return is fine — you just can't do both.)
Not under IRS examination when the change is filed, or the audit-protection rules get complicated.
File it right: Form 3115 attached to the timely filed (including extensions) return for the year of change, with the duplicate copy sent to the IRS in Ogden.
The takeaway
Bonus depreciation can't be deferred, but its recognition can be steered. Buy the property, depreciate it as a building, hold the cost seg study until the year that has real estate professional status, a business-character gain to absorb the loss, and room under the excess business loss cap — then file Form 3115 and take the whole thing at once.
The sequencing is simple. The gating rules are not, and getting one of them wrong (an accidental election out, an hours log that doesn't hold up, a stock gain that can't absorb the loss) turns a six-figure deduction into a carryforward. This is a plan worth modeling before the property closes, not after.
Closing on rental property this year? We model the purchase-year and year-of-change scenarios side by side — federal and California — so you know before closing which year the deduction should land in.
This article is general information, not tax advice. The example is hypothetical and simplified; rates, thresholds, and results depend on facts specific to each taxpayer and on law as of the date of publication. Consult your tax advisor before acting.
