The investors getting the most out of cost segregation aren't just doing studies - they're doing tax planning to make sure the losses hit their tax return
Rental real estate is passive under IRC §469 by default. Your $200,000 year-one depreciation loss from a cost seg study does nothing for your W-2 or business income unless you break out of passive treatment.
The IRS default rule under IRC §469 treats every rental property as its own separate passive activity.
That matters because passive losses can only offset passive income. An $80,000 depreciation loss from your rental portfolio does nothing for your W-2 income unless you break out of passive treatment.
There are two legitimate ways to do that: the STR loophole and Real Estate Professional Status (REPS). Both require material participation. Both are harder to achieve when you own multiple properties. That's where the grouping election comes in.
Path 1 - The STR Loophole and Reg. §1.469-4
Why Short-Term Rentals Are Different
Under Temp. Reg. §1.469-1T(e)(3)(ii)(A), a rental activity is excluded from the passive activity rental rules when the average period of customer use is seven days or less.
Read that carefully. A short-term rental with an average stay of seven days or fewer is NOT a rental activity under §469. It's classified as a non-rental trade or business. That's the loophole. You escape the passive activity rental rules entirely without needing REPS.
The catch: you must materially participate in the activity. Without material participation, losses stay passive.
The Seven Tests for Material Participation
Per Temp. Reg. §1.469-5T(a), a taxpayer materially participates in an activity if they meet at least one of seven tests. The three most relevant for STR investors:
- More than 500 hours of participation in the activity during the year
- More than 100 hours, AND no other individual spends more time on the activity than you
- Participation that constitutes substantially all participation in the activity for the year
You can combine your hours with your spouse's hours to meet these thresholds.
The Problem With Multiple STRs
One STR? Getting to 100 hours is doable. Three STRs? Five STRs? The math gets ugly fast.
Under the default rule, each property is its own activity. You need to hit a material participation test independently for each one. If you fail on any property, that property's losses stay passive.
The Fix - Reg. §1.469-4 Grouping
Treasury Regulation §1.469-4 allows a taxpayer to treat multiple activities as a single activity for material participation purposes, as long as they constitute an "appropriate economic unit."
Group your five STRs together, and your combined hours across all five are measured against a single material participation threshold. Instead of needing 100 hours per property, you pool everything into one bucket.
What Qualifies as an Appropriate Economic Unit?
The regulation identifies five factors. No single factor controls. The IRS weighs all of them:
- Similarities and differences in the types of business
- The extent of common control
- The extent of common ownership
- Geographic location
- Interdependencies between or among the activities - shared management, marketing, booking, or services
Five Airbnb cabins on the same lake, booked through the same account, under the same LLC, managed by the same system: strong case. Five STRs spread across five states with different management structures: much harder.
What STR Grouping Gets You
When you group under §1.469-4 and materially participate in the group, losses from the entire portfolio are non-passive. You can deduct them against W-2 income, business income, or any other active income source.
This is the core benefit. A $200,000 combined paper loss from cost segregation and depreciation across your STR portfolio - applied directly against your active income. That's a real number for a lot of high earners.
Path 2 - Real Estate Professional Status and Reg. §1.469-9(g)
What REPS Actually Requires
Under IRC §469(c)(7)(B), a taxpayer qualifies as a real estate professional if:
- More than 750 hours of services are performed during the year in real property trades or businesses in which the taxpayer materially participates, AND
- More than 50% of all personal services performed during the year are in real property trades or businesses in which the taxpayer materially participates
This is a per-person test. You cannot combine both spouses' hours to qualify one spouse. One spouse must independently clear both hurdles.
Once you qualify for REPS, your rental activities are treated as non-passive - but ONLY for properties where you also materially participate.
The Problem With Multiple Long-Term Rentals
Own twenty long-term rentals? Under the default rule, each is a separate activity. An RE Professional still needs to materially participate in each individual property. Twenty separate participation tests, twenty sets of time logs.
In practice, most people with large rental portfolios cannot demonstrate meaningful participation in every single property. Without it, the losses stay passive even with REPS.
The Fix - Reg. §1.469-9(g) Grouping
Treasury Regulation §1.469-9(g) gives qualifying real estate professionals the ability to elect to treat ALL rental real estate activities as a single activity for purposes of the material participation tests.
One election, one pooled hour count, one material participation test across the whole portfolio.
The Critical Difference - This Election Is All-or-Nothing
This is where STR grouping and REPS grouping split completely.
The §1.469-4 election (STR path) is selective. You choose which specific activities to group.
The §1.469-9(g) election (REPS path) is all-or-nothing. Once made, it applies to every rental real estate activity you own. You cannot include some and exclude others.
That creates real planning complexity, which I'll cover below.
STRs Do Not Belong in the REPS Grouping Election
This is the piece most people get wrong.
Because STRs with an average stay of seven days or fewer are NOT rental activities under §469, they cannot be included in the §1.469-9(g) election. That election is for rental real estate activities only.
So an investor who owns both short-term rentals and traditional long-term rentals is operating in two separate regulatory worlds at the same time:
- STRs fall under the §1.469-4 non-rental trade or business framework
- Long-term rentals fall under the §1.469-9(g) REPS grouping framework
If you have both, you need both elections - kept entirely separate from each other.
The Pitfalls
Ungrouping Is Nearly Impossible
A grouping election under §1.469-4 generally cannot be revoked unless facts and circumstances change materially. The regulations are explicit that a taxpayer may not regroup simply because a different grouping would be more tax-advantageous.
Think carefully before you elect. A profitable STR grouped with loss properties might not serve you in later years.
The All-or-Nothing REPS Trap
Because §1.469-9(g) captures every rental real estate activity, passive syndication investments get swept into the group.
Here's what that means: if you're an RE Professional who makes a grouping election, and you also hold a limited partnership interest in a real estate deal where you have no operational role, that passive investment is now part of your grouped activity. Your hour count across the whole group still needs to clear material participation. A passive deal with zero hours dilutes the group.
Some practitioners try to avoid this by not making the §1.469-9(g) election at all and instead demonstrating material participation property-by-property. That's viable for smaller portfolios but becomes impractical at scale.
The REPS Grouping Election Does Not Create Non-Passive Treatment by Itself
Making the election is step one. You still need to actually materially participate in the grouped rental activity. RE Professional qualification plus the grouping election plus material participation in the group equals non-passive treatment.
Miss any one of those three, and you're back to passive.
Profitable and Loss Properties in the Same Group
When you group activities, you measure net results across the group. If your STR in Scottsdale generates $40,000 of net income and your STR in the Smoky Mountains generates a $90,000 loss, the grouped activity shows a $50,000 loss.
That sounds fine until you consider disposition. When you eventually sell the Scottsdale property and want to recognize suspended passive losses tied to it specifically, you can't - because it's not a separate activity anymore. Loss release on partial disposition of a grouped activity is complicated and generally requires disposition of substantially all of the group.
Property Managers Can Kill Material Participation
If a third-party property manager spends more hours on your STR than you do, you fail the 100-hour test. Grouping cannot save you from that.
Under the material participation rules, participation by the taxpayer does not include work that is not customarily performed by an owner of the activity, and management work performed by someone other than the taxpayer counts against you on the 100-hour/no-one-else test.
Self-managing your STRs - or at minimum documenting clearly that YOUR hours exceed the manager's hours - is not optional.
The Scenario Most People Are In
Here's what I see with high-earning clients considering the STR loophole:
They have W-2 or business income, usually $400,000 to $1,000,000. They cannot qualify for REPS because they're not in real estate full time. They buy one or two STRs and materially participate without issue. Then they buy a third and fourth, and suddenly the hour count per property gets thin.
The §1.469-4 grouping election solves this cleanly. Group all four STRs into one activity. Pool your hours. Hit material participation once. Apply losses against income.
For a client in the 37% bracket with $150,000 of STR paper losses after cost segregation and depreciation, that's $55,000 in real tax savings. That's not theoretical. That's the math.
What You Should Actually Do
First, identify which path applies to you. If you have long-term rentals and spend most of your professional time in real estate, REPS and §1.469-9(g) grouping is worth evaluating. If you have short-term rentals and a full-time job or business elsewhere, the §1.469-4 grouping election is your tool.
Second, make the grouping election the RIGHT year. Grouping elections are documented on the tax return for the first year they apply. Retroactive elections are not available.
Third, document your hours the RIGHT way. A spreadsheet filled in on December 28th does not constitute a contemporaneous time log. If you're audited, the IRS will request calendar records, booking confirmations, contractor communications, and guest correspondence to corroborate your hours.
Fourth, get qualified counsel before making either election. The mechanics are not complicated. The planning around which activities to include, whether to group at all, and how the election interacts with your broader portfolio is where mistakes get made.
The Bottom Line
Two strategies. Two grouping elections. Two separate regulatory frameworks.
The §1.469-4 election is for STR investors who need to pool hours across multiple short-term rental properties to meet material participation.
The §1.469-9(g) election is for qualifying real estate professionals who need to treat the entire long-term rental portfolio as one activity.
STRs don't belong in the REPS grouping, and long-term rentals don't belong in the §1.469-4 grouping. If you have both, you need both elections kept entirely separate.
Get this right, and it's one of the most powerful tools in real estate tax planning.
Get it wrong, and you've made an irrevocable election that costs you for years.
This post is for educational purposes only. Nothing here constitutes legal or tax advice for your specific situation. Seek qualified counsel before making any grouping elections.
