I was wondering if anyone could provide some insight on how to distribute Home Office and auto expenses across multiple businesses. I have a web hosting business, three rental properties, and a regular full time job. In the past I deducted my vehicle expenses on the web hosting only, and deducted my home office expense under 1 of the rental properties in Turbo Tax. Should I split the cost of the Home office expense across the three rental properties and the web hosting evenly or should I only take the deduction against one. For example: If the home office expenses were 4000.00 Rental property 1 - 1,000 rental property 2 - 1,000 rental property 3 - 1,000 web hosting biz - 1,000 Or should it be all under Webhosting = 4000.00 Also, for the vehicle if I used it for all business purposes, and no personal use should I take a % of the standard mileage for each business. For example: SM = 4400 Rental property 1 - 1,100 rental property 2 - 1,100 rental property 3 - 1,100 web host - 1,100