The IRS pubs can not possibly cover all possible scenarios in a coherent manner. But I'm sure your situation is covered. It can be rather difficult to "dig it out" though, so to speak.
If you live in a 2-unit complex, where each unit has it's own entrance, bathing facilities, sleeping facilities and cooking facilities, then you basically have a duplex where you live in one unit and rent out the other. Ie; each unit can operate completely independent of the other without the sharing of "any" facilities. Otherwise, if one or more of those facilities are shared, you have a single family unit where you rent out "a part of" your primary residence.
You have several options for how to deal with this on y our taxes. Each option has it's pros and cons. I'll be happy to explain each when I know more precisely what you have. It does not matter if the utilities (electric, water, gas, etc) are metered separately or not. But I would need to know if they are or not so I can provide you more details on your tax reporting options.
