You can use single family, but you need to allocate your son's personal use and the business use percentage. You need to take the total square footage of the condo. How much space is exclusively used by the other renters? You may only deduct that percentage for all of your expenses. For example, the common areas such as kitchen, dining, and living rooms are more than likely used by your son. Therefore, that portion of the square footage is not deductible. So if the total exclusive rented space is 250 square feet out of a 1200 square foot condo, you can only deduct 21% of the expenses.
If you do not rent the condo to make a profit, the other option is to report this income as Not for profit rental income. You will report the rental income received as Other Income. This will reflect on Line 21 of your 1040. You can then deduct the portion of your rental expenses on your Schedule A - as other miscellaneous itemized deductions.
