1. What a cost segregation study does
A building normally depreciates over 27.5 years (residential) or 39 years (commercial). A cost segregation study breaks the purchase price apart and reclassifies components like flooring, cabinetry, dedicated electrical, and land improvements into 5, 7, and 15-year property, so a large slice of the basis depreciates on much shorter schedules.
On the federal return, that reclassified property also qualifies for bonus depreciation, which restores a 100% first-year write-off for qualifying property acquired and placed in service after January 19, 2025. States set their own rules, which is where South Dakota comes in.
2. South Dakota and federal bonus depreciation
South Dakota imposes no individual income tax and no general corporate income tax, so there is no state return on which IRC 168(k) bonus depreciation could be allowed or disallowed. Whatever a real estate investor claims federally, including permanent 100% bonus under the One Big Beautiful Bill Act for property acquired after January 19, 2025, is simply the final answer; there is no state addback, no separate state depreciation schedule, and nothing changed for individuals in the 2025 or 2026 legislative sessions. The one income-measured tax the state does levy, the bank franchise tax on financial institutions (SDCL ch. 10-43), starts from federal taxable income with a static IRC conformity date that the legislature refreshed via HB 1028 (2025, IRC as of Jan 1, 2025) and SB 19 (signed Feb 2026, IRC as of Jan 1, 2026, which captures OBBBA), but that tax applies only to banks, savings and loans, and similar institutions, not to real estate investors.
Worked example
A $1,000,000 building, with and without a study
Illustrative only. A residential rental purchased for $1,000,000 of building basis (land excluded), acquired and placed in service after January 19, 2025.
Building basis
$1,000,000
Reclassified to 5, 7, and 15-year property (25%)
$250,000
Federal first-year deduction at 100% bonus
$250,000
Year 1 on that $250,000 without a study (27.5-year straight line)
about $9,100
South Dakota levies no individual income tax, so the federal deduction above is the whole story for individual owners and pass-through investors.
Model your own numbers with the tax strategy projector.
3. Section 179 in South Dakota
No state income tax means no Section 179 conformity question and no state-specific cap. Federal Section 179 (OBBBA raised the cap to $2.5M with a $4M phase-out threshold for 2025) applies untouched because the federal return is the only income tax return a South Dakota investor files.
4. Does it still help in South Dakota?
Yes, fully: a cost segregation study delivers 100% of its benefit because the federal deduction is the entire income tax picture; reclassified 5/7/15-year property takes permanent 100% bonus federally with zero state clawback, addback, or recovery schedule.
- •South Dakota has no individual income tax, no corporate income tax, no personal property tax, and no business inventory tax; it is one of only a handful of states with neither personal nor corporate income tax.
- •The only income-measured tax is the bank franchise tax on financial institutions (SDCL ch. 10-43), computed from federal taxable income with a static IRC conformity date: HB 1028 (enacted Feb 2025) set it at Jan 1, 2025, and SB 19 (signed Feb 2026) advanced it to Jan 1, 2026, bringing OBBBA provisions into that tax; it never applies to real estate investors or operating businesses.
- •Because there is no state income tax, MACRS recovery periods (5/7/15/27.5/39-year), bonus depreciation, and Section 179 questions are all resolved entirely on the federal return; there is no state depreciation tracking or dual-basis recordkeeping for South Dakota property.
- •South Dakota funds itself through sales/use tax (state rate 4.2%), property tax, and a 2% contractor's excise tax on construction services, so the practical state-tax costs of a rental property are property tax and excise tax embedded in construction or renovation bids, not income tax.
- •Unlike Texas (franchise/margin tax) or Washington (B&O and capital gains excise), South Dakota has no gross-receipts or franchise-style tax on ordinary LLCs, partnerships, or corporations holding real estate.
5. The exit: recapture and timing
The accelerated deductions come back into view when you sell. Gain attributable to the 5, 7, and 15-year property is Section 1245 recapture, taxed at ordinary rates, and the straight-line depreciation on the building itself is unrecaptured Section 1250 gain, taxed at up to 25%. A study does not create that bill, it moves deductions forward, but the timing of the sale decides how much of the benefit you keep.
Two levers manage the exit. A 1031 exchange defers both flavors of recapture along with the rest of the gain, and simply holding the property lets the time value of the early deductions do its work; most owners want a 3 to 5 year horizon before a taxable sale for the math to stay comfortably positive. Model the exit before you commission the study, not after.