Yes. A co-host is an individual, and the 100-hour test in Treas. Reg. §1.469-5T(a)(3) requires that no other individual participated in the activity more than you did. If your co-host put in more hours on the property than you, the second half of the test fails no matter how many hours you logged. The one exception is a co-host who is your spouse, whose participation is generally attributed to you under §469(h)(5). For everyone else, the co-host's hours are the number your hours have to beat, and you need a record of both.
A co-host is an individual, so the comparison applies
The regulation's wording is "any other individual (including individuals who do not own any interest in the activity)." Ownership is irrelevant. Payment is irrelevant. A friend who handles check-ins for free is in the comparison exactly as a paid professional is. The only question is how many hours each person actually spent on the activity during the year.
That makes co-hosting different from hiring a management company. A company spreads a property across several employees, each with modest hours. A co-host is usually one person doing many things — messaging, turnovers, restocking, the occasional repair — and a single person's hours add up fast. The 100-hour test guide explains the second half of the test in general; this post is about the co-host case specifically.
Three co-host models and how each is counted
Family member (not a spouse). A parent or adult child who lives near the property and "keeps an eye on it" often does far more than the owner realizes: every lockout, every delivery, every cleaner no-show. Their hours count against you in full. The informal arrangement is the problem, because nobody is writing anything down.
Friend or neighbor. Same rule, often with the same record-keeping gap. Trading a few free nights for help does not change the analysis; it just means there is no invoice to reconstruct from.
Professional co-host. A paid individual running your listing under a co-hosting agreement. Their hours count against you, but the professional relationship makes them easier to document: there is usually a task list, a fee structure, and platform access that leaves timestamps.
In all three cases the arithmetic is the same. Owner hours must exceed 100 and must exceed the co-host's. If the co-host does the turnovers and the owner does pricing and approvals, the co-host is frequently ahead.
How to get a co-host's hours
You need a defensible number, not a signed timesheet. Sources, in order of strength:
- Their own log. Ask the co-host to keep entries the same way you do: date, task, minutes. A professional co-host who is asked at the start of the engagement will usually agree. STR Tracker's other-participants tracker lets you add a co-host to each property and log their hours next to yours, so the comparison is a running number rather than a March surprise.
- Platform message timestamps. If the co-host has listing access, the inbox shows who replied to what and when. It proves activity, not duration, but it anchors an estimate.
- Turnover count × typical time. From the booking calendar, count the turnovers the co-host handled and apply a realistic per-turnover figure you can explain.
- A written monthly summary. At month end, a short note from the co-host — "12 turnovers, 3 lockouts, 1 plumber visit, roughly 40 hours" — dated when it was written.
Record the method with the number. "Co-host: 310 hours, from their shared log" reads very differently from "co-host: maybe 100."
When the co-host is your spouse
Participation by a spouse is generally taken into account as participation by the taxpayer for purposes of the material participation tests, whether or not the spouse has an ownership interest and whether or not you file jointly. In the co-host context that means a spouse's turnover hours are not on the other side of the comparison; they are on your side.
This rule is specific to spouses. It does not extend to unmarried partners, adult children or siblings, and it does not apply to the 750-hour test for real estate professional status, where spouses' hours are not combined. Keep each spouse's entries separate in the records even though they may be combined for the test; the spouse hours guide explains why.
Rebalancing: which tasks to take back
If the comparison is going the wrong way mid-year, the honest fix is to do more of the work, not to describe the co-host's work differently. Tasks that owners commonly take back because they are real, loggable and do not require being on-site:
- All guest messaging, inquiries and reviews
- Pricing, calendar management and listing updates
- Vendor sourcing, quotes and scheduling
- Supply ordering and inventory
- Bookkeeping for the activity
Tasks that require presence — turnovers, inspections, repairs — are worth taking back on visits, and they tend to be the most credible hours in a log. If the co-host lives at the property's location and you do not, be realistic about what you can shift.
The alternative some owners consider is the 500-hour test, which has no comparison at all. Whether that is achievable depends on the property and the owner's other commitments, and is a conversation to have with a CPA in the first quarter, not the fourth.
Red flags
A log that will draw questions:
- The co-host "does everything" according to the listing, the reviews and the message history, while the owner claims 100-plus hours of unspecified management.
- The owner's entries are round numbers in categories, and the co-host's hours are not recorded at all.
- The co-host's hours are recorded, but at a level nobody who has run a short-term rental would believe — 30 turnovers at half an hour each.
- The co-host is paid a percentage of revenue typical of full management, and the owner's log shows no corresponding drop in their own hours.
Understating a co-host's time to win the comparison is not a strategy; it is a misstatement that the platform's own timestamps can contradict.
An example month
Fictional numbers for one property in a busy month, 11 turnovers:
| Person | Tasks | Hours |
|---|---|---|
| Co-host | 11 turnovers at 2.5 h; 2 lockouts; restocking runs | 33.5 |
| Owner | Messaging (logged per event), pricing, two vendor quotes, one on-site inspection visit | 21.0 |
Over twelve similar months the co-host is near 400 hours and the owner near 250. The owner is comfortably past 100 and fails the test. Now take the turnovers back for four months of the year and add the supply ordering: the owner rises, the co-host falls, and the comparison may flip. The point is not the specific numbers. It is that both columns have to exist before anyone can tell.
What to write down
For each property: your entries, the co-host's entries or your documented estimate of them, and the method you used to get the estimate. Ask the co-host today, not in December. If you are starting fresh, begin a free trial, add the co-host as a participant on each property, and watch the two totals together all year.