Updated August 3, 2026. Quick answer: letting your son or daughter use the cabin counts as your own personal use — even if they pay full market rent. There is an exception, but it requires the property to be that person’s principal residence, which a vacation home almost never is. Charging family rent does not convert the days.
Family use is your use
(d)(2) Personal use of unit. For purposes of this section, the taxpayer shall be deemed to have used a dwelling unit for personal purposes for a day if, for any part of such day, the unit is used—(A) for personal purposes by the taxpayer or any other person who has an interest in such unit, or by any member of the family (as defined in section 267(c)(4)) of the taxpayer or such other person; (B) by any individual who uses the unit under an arrangement which enables the taxpayer to use some other dwelling unit (whether or not a rental is charged for the use of such other unit); or (C) by any individual…
— IRC 280A(d)(2) and 280A(d)(3)
Look at what (d)(2) does. A day counts as your personal use if the unit is used for personal purposes by you, by anyone else with an interest in it, or by any member of the family of either. There is no rent condition attached to the family limb.
The exception, and why it usually will not help you
Subsection (d)(3) provides the escape: a taxpayer is not treated as using the unit personally where it is rented at a fair rental, to any person, for use as that person’s principal residence.
Principal residence is the whole hinge. A cabin that a family member uses for holidays, or for a summer, or at weekends, is not their principal residence — so the exception does not reach it, and the days remain your personal use no matter what they paid.
Two precisions worth having exactly right. (d)(3)(A) says “any person”, not “family member” — the family framing appears only in the subsection heading, so the exception is about principal-residence use rather than about who the occupant is. And where the occupant has an ownership interest in the property, (d)(3) applies only where that arrangement is a shared equity financing agreement — which matters directly for a cabin already co-owned by siblings.
Why the day count decides real money
Because personal use is what determines whether the property is treated as a residence, and that governs how much of the expenses can be deducted at all:
For purposes of this section, a taxpayer uses a dwelling unit during the taxable year as a residence if he uses such unit (or portion thereof) for personal purposes for a number of days which exceeds the greater of—(A) 14 days, or (B) 10 percent of the number of days during such year for which such unit is rented at a fair rental.
— IRC 280A(d)(1)
So the test is the greater of 14 days or 10% of the days rented at fair rental. A family member’s stay lands on the personal side of that comparison, which pushes you toward residence treatment and away from deducting expenses — the opposite of what an owner charging rent usually assumes is happening.
What to do instead of guessing
- Keep an actual log of nights and who used them. The whole analysis is a day count, and reconstructing a year of family visits afterwards is not a record.
- Do not assume charging rent solves it. On these facts it usually changes nothing except that you now have income to report.
- If a family member genuinely lives there as their main home, that is a different arrangement and (d)(3) may apply — but check the ownership-interest rule first if they are also an owner.
- Get advice before restructuring. This interacts with how the property is held, and the answer changes if it moves into an entity.
Related: the under-15-day rule · keeping the cabin in the family · renting an inherited house to a sibling.
General information drawn from the Internal Revenue Code and IRS publications, not legal or tax advice. Co-ownership structures, partition rights, deeds and recording are STATE law and differ materially. Insurance wording controls what is covered, and a seasonally unoccupied property is treated differently by different insurers. We sell no property and receive nothing from any insurer.