How to Expense Carriage House Rental

Hi

We have a carriage house that we rent out. 

It has its own Drive way. 

 

Water and sewage are separate accounts for the carriage house, so I am going to expense them, but How do I expense

- landscaping, snowplowing, tree work (esp given its separate driveway)

- what about property taxes, home owners insurance. 

It appears some blogs recommend prorating it based on square footage but I was not able to find an actual IRS guideline or article, so I just wanted to confirm. 

 

- depreciation : any drawbacks on claiming depreciation? does it affect the main house negatively if and when we were to sell it?