See IRS Publication 527 Residential
Rental
Property page 19 - https://www.irs.gov/pub/irs-pdf/p527.pdf#page=19
Used as a home but rented less than 15
days.
If you use a dwelling unit as a home and
you rent it less than 15 days during the year, its
primary function is not considered to be rental
and it should not be reported on Schedule E
(Form 1040). You are not required to report the
rental income and rental expenses from this activity.
The expenses, including qualified mortgage
interest, property taxes, and any qualified
casualty loss will be reported as normally allowed
on Schedule A (Form 1040).
