If the latter, there are lenders out there that will use your actual rental rates as long as you have lease agreements, 2 months of rental receipts, and the actual rent is within 20% variance of the market rents on the appraisal.

The tenant is less likely to trash a place or violate the lease if you hold a large chunk of money. 

For single-family and multi-family rentals - plan to put 20-25% down on investment properties.If you find a rental from 2-4 units with a month to month lease or a vacant unit that you could technically move into/would move into after buying within 60 days - plan to put 3.5-5% down. 

It has been a couple days and have not seen an answer.If you own a rental property and you have a signed lease at the minimum of 1+ year, does that rental property mortgage (traditional investment loan) still count against your DTI?

The IRS requires the hours to be specifically in real estate trades or businesses, which typically means activities directly related to owning, developing, operating, or managing real estate properties.IRS Publication 925 outlines what counts as real estate trade or business activities, like development, construction, acquisition, management, leasing, and rental operations.

At the same time, look to see if he left any contact information behind and reach out to family to determine his status.If you can't contact anyone soon, I would consider moving his belongings to storage, terminating the lease, and finding a new roommate.Because you are in California, I would consult an attorney.

The tenant has caused damage and broken the lease so she is going to vacate in December.

Who actually signs the lease?

Highly advise taking the ADU and the first floor unit and creating a master "single lease'.

@Raghavendra Jakkani first, agree with everyone else about every occcupant 18+ being screened & signing the lease, with one exception - an occupant that is claimed on another occupant's tax return as a dependent.