@AmeliesUncle
here's from the reg
https://www.bradfordtaxinstitute.com/Endnotes/Prop_Reg_1_280A-3d1.pdf
(b)Short rental period. If a dwelling unit used by the taxpayer as a residence during the taxable
year is actually rented for less than 15 days during the taxable year,
(1) No deduction otherwise allowable because of the rental use shall be allowed, and
(2) The rental income shall not be included in gross income
their rental period is zero because of charging below market rent which makes all days person use days.
