It depends. When you put in your home office expenses, they will be prorated based on either the amount of space you use or the number of rooms you use for your business. If you and the other person are using different rooms/parts of the house to work, then you each put in the total expense. But if you are both sharing the same room/space, then you would put half the amount for each shared expense.
Ex: Bob & Teena have a house with 10 rooms. Bob use the garage for his business, while Teena uses a room that she has converted to a lab. They would both enter the total amount of their home-office expenses, and TurboTax will claim 1/10th of the expense for each of them.
Meanwhile, Jono & Uma also lived in a house with 10 rooms. They both ran their own businesses from home, but they shared the same office. In their case they would put half of their total shared expenses each. If they had $1000 mortgage expense, then Jono would enter $500 on his return & Uma would enter $500 on hers.
