Basically, the percentage of your floor space that is classified as rental, is the percentage of space that is "exclusive to the renter".
When it comes to the utilities, you actually have two choices on how to figure those.
One way is to claim the percentage of utilities cost (water, electric, cable, heat, etc.) that is equal to the percentage of floor space that is exclusive to the renter.
Another way is to divide the utilities by the number of people living in the house. You live there as the owner, and you have a paying tenant occupying say for example, 10% of the floor space. With two people sharing the utilities, you can claim 50% of those utilities on SCH E. If you are married then you wife lives in the house also. With a tenant that would make three people. Then you could claim 1/3 of your utility expenses on the SCH E.
You can pick the way that's most beneficial to you, and you don't have to use the same method each year when it comes to the utility costs.
The percentage of floor space that is exclusive to the renter matters, mostly for the mortgage interest deduction, property tax deduction, and property insurance deduction you can claim on the SCH E.
One thing to note. If you have 2 or more baths and one of those baths can only be accessed from the room that is exclusive to the renter, then you can include that bath when figuring your percentage of floor space. Every little bit helps.
Now, if 2022 was the first year you did this, my bet is that the first year depreciation will be wrong. If it is wrong, let me know and I'll show you how to make it right without having to do an over-ride, so you can still e-file.
To confirm the depreciation, see IRS Publication 946 at https://www.irs.gov/pub/irs-pdf/p946.pdf Then use the MACRS worksheet that starts on page 37. For line 6 of that worksheet, you'll use table A-6 on page 72.
