Code section · 2017
IRC §168(g) Alternative Depreciation System
26 U.S.C. §168(g)
Internal Revenue Code
The facts
ADS uses longer, straight-line recovery periods: 30 years for residential rental property placed in service after 2017, 40 years for nonresidential real property, and 20 years for QIP.
What it holds
ADS is mandatory for the categories listed in section 168(g)(1), including property of an electing real property trade or business under sections 168(g)(8) and 163(j)(7)(B). Section 168(k)(2)(D) excludes property to which ADS applies from bonus-eligible qualified property, determined without regard to the voluntary section 168(g)(7) election. So a voluntary ADS election does not kill bonus, but mandatory ADS status does.
Why it matters for your study: The interest-expense election that helps on section 163(j) can quietly kill bonus depreciation on the building, QIP, and residential property. We confirm a client's ADS status before promising bonus numbers.
Background
Section 168(g) houses the alternative depreciation system, or ADS. It uses straight-line depreciation over longer recovery periods than the regular system. After the 2017 law, the headline ADS periods are 30 years for residential rental property, 40 years for nonresidential real property, and 20 years for QIP.
ADS matters most because of a trade the 2017 law created. A real property business squeezed by the section 163(j) interest expense limit can elect out of that limit as an electing real property trade or business. The price of that election is mandatory ADS on its buildings, QIP, and residential property.
What it established
Section 168(g)(1) lists the property that must use ADS. The list includes property of an electing real property trade or business under sections 168(g)(8) and 163(j)(7)(B), along with other categories. Separately, section 168(g)(7) lets any taxpayer choose ADS voluntarily.
The bonus interaction is the trap. Section 168(k)(2)(D) excludes from bonus-eligible qualified property any property to which ADS applies, determined without regard to the paragraph (g)(7) election. Read carefully, that means a voluntary ADS election does not cost you bonus eligibility, but property forced onto ADS by the mandatory list cannot get bonus.
How it shows up in a study
ADS status is a front-of-engagement intake question. If the owner made the real property trade or business election for section 163(j), the building, its QIP, and residential property are on mandatory ADS, and the bonus projections must be built without bonus on that property. Promising 100 percent bonus to an electing RPTOB is a real-world malpractice pattern this section prevents.
The study also uses the ADS periods themselves. Affected assets are scheduled at the ADS lives, and the report flags the election so the depreciation schedules tie to the client's section 163(j) posture.
What it does not mean
Mandatory ADS does not make cost segregation pointless. The 30 and 40-year ADS periods apply to the real property; assets properly classified as shorter-life property carry their own much shorter ADS periods. For example, Rev. Rul. 2003-54 shows class 57.0 property at 9 years under ADS and class 57.1 at 20 years. Reclassification still moves dollars dramatically forward.
It also does not mean every ADS taxpayer loses bonus. The statute itself draws the line: voluntary ADS under (g)(7) leaves bonus eligibility intact, while the mandatory categories in (g)(1) are excluded. Getting that distinction backwards, in either direction, produces wrong numbers.
Primary source
Read the official text for yourself, or share it with your advisor.
- Category
- Bonus depreciation & expensing
- Applies to
- All property types
- Status
- Vetted
This page explains a tax authority in plain words. It is not tax advice for your situation. The way this authority applies to your property is reviewed by a licensed tax professional. Citation is provided so you or your advisor can read the primary source.