when you read a publication read the whole pub. there can be parts that in effect change what was stated earlier. like what's on page 19
I do not want to profit off my family, so she is just paying me enough to cover my monthly expenses: mortgage, property tax, and HOA. Needless to say it is significantly under market value in terms of "rent".
there is a rule for this situation. any day rented below fair market value is a personal use day. therefore it seems for the year either you used it or your sis used it. therefore, 100% of the use is considered personal use days.
from page 19 of the pub
Used as a home but rented less than 15 days (any day rented at less than fair value to a family member is not a rental day (IRC SEC 280A) so your rental days are zero. If you use a dwelling unit as a home and
you rent it less than 15 days during the year, its primary function isn’t considered to be rental
and it shouldn’t be reported on Schedule E (Form 1040). You aren’t required to report the
rental income and rental expenses from this activity. Any expenses related to the home, such
as mortgage interest, property taxes, and any
qualified casualty loss, will be reported as normally allowed on Schedule A (Form 1040). See
the Instructions for Schedule A for more information on deducting these expenses
if you were to complete schedule E fair rental days would be zero and personal use days would be 365.
i'm not even sure Turbotax would allow 0 to be entered as FRV days because nothing would get reported.
Prop. Reg. Section 1.280A-3(d)(1)
https://www.bradfordtaxinstitute.com/Endnotes/Prop_Reg_1_280A-3d1.pdf
Deductibility of expenses attributable to the rental of a dwelling unit used as a residence
(a)Scope. This section provides rules for determining the deductibility of expenses attributable to
the rental of a dwelling unit used as a residence. Note that paragraph (c) of this section applies to
any dwelling unit used by the taxpayer for personal purposes on any day during the taxable year,
whether or not the taxpayer is treated as using the unit as a residence. See §1.280A-1 for the
general rules under section 280A.
(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.
