How do I calculate rental expense if I rent out portion of my home(basement). I have bungalow house. Both of upstair level and basement are same size. I rent out 7 months

I did my renovation after my tenants left the house. Also, I have other expenses like property taxes, mortgage interest rate and insurance. How do I calculate those part of expense as my rental expenses. Thank you.

Any actual repairs or normal wear and tear after tenants leave is deductible. A complete renovation can become a capital expense which is not deductible in the same way.  You take the total square footage of the house and the square footage of the rental unit.  Divide the rental sq feet by the total sq ft to get a percentage. Once you put in the number of square feet on the entry page, the software will calculate it.

If you renovated your basement prior to renting it, you cannot claim the cost as a deduction against the rent.  You add that cost to the value of the residence as a whole.  The renovation is considered a capital improvement rather than an expense.