This is correct.
This is what the IRS says:
If you rent part of your property,
you must divide certain expenses between the part of the property used for
rental purposes and the part of the property used for personal purposes, as
though you actually had two separate pieces of property.
You can deduct the expenses related
to the part of the property used for rental purposes, such as home mortgage
interest, qualified mortgage insurance premiums, and real estate taxes, as
rental expenses on Schedule E (Form 1040). You can also deduct as rental
expenses a portion of other expenses that normally are nondeductible personal
expenses, such as expenses for electricity or painting the outside of the
house.
There is no change in the types of
expenses deductible for the personal-use part of your property. Generally,
these expenses may be deducted only if you itemize your deductions on Schedule
A (Form 1040). Repairs to your personal portion are not deductible.
How to divide expenses. If an expense is
for both rental use and personal use, such as mortgage interest or heat for the
entire house, you must divide the expense between rental use and personal use.
You can use any reasonable method for dividing the expense. It may be
reasonable to divide the cost of some items (for example, water) based on the
number of people using them. The two most common methods for dividing an
expense are (1) the number of rooms in your home, and (2) the square footage of
your home.
Duplex. A common
situation is the duplex where you live in one unit and rent out the other.
Certain expenses apply to the entire property, such as mortgage interest and
real estate taxes, and must be split to determine rental and personal expenses.
Example.
You own a duplex and
live in one half, renting the other half. Both units are approximately the same
size. Last year, you paid a total of $10,000 mortgage interest and $2,000 real
estate taxes for the entire property. You can deduct $5,000 mortgage interest
and $1,000 real estate taxes on Schedule E (Form 1040). If you itemize your
deductions, you can deduct the other $5,000 mortgage interest and $1,000 real
estate taxes on Schedule A (Form 1040).
From
<https://www.irs.gov/publications/p527/ch04.html#en_US_2016_publink1000219159>
