If my llc or sole proprietorship owns a garage and I rent half of it out to someone else for $600/mth and the mortgage cost $800, can I write of the remaining $200?

[TaxGuyBill]

The mortgage cost has nothing to with it.  You can deduct (1) mortgage interest, (2) real estate taxes, (3) insurance (4) utilities, and (5) depreciation (a full year of depreciation would be the purchase price divided by 39 years).

If you only rent out half of it, then you can only deduct half of those expenses.

[AmandaR1 · Accepted solution]

You would only write-off your portion of the garage, if it's being used for a business purposes. As explained in a comment, some expenses can be deducted for the rental portion, but not the mortgage payment itself.  

Instead of deducting your mortgage payment, you'll add the garage to the software and take depreciation based on the cost you paid for the property. If the property is part a rental and part for business, you'll need to add it for Assets/Depreciation under both your Rental and your Self-Employed Business. 

When you add your garage as a rental property under the Rental & Royalty Income and Expense section, the software will walk you through deducting these expenses. 

If you are using the other portion of the garage for your business, then you'll write off all of your related expenses (again except the actual mortgage payment) under you Self-Employed Business Income and Expenses. 

• Mortgage interest under Interest
• Real estate taxes under Taxes and Licenses
  
• Depreciation under Assets/Depreciation
  

Let me know if you have any questions.