Convert primary residence to rental

[Uchenna Okoye]

I signed a purchase contract over 9 months ago to purchase a new construction single family home. At the time, I hoped to have my mom stay with me. I am single and not married or with kids. The house was delayed in construction and during that time a lot of changes happened. We had a new born in the family! My mom needs to stay closer to family on the east coast to help with raising my niece and she would not be close to me. 

Can I downscale and rent the house? I just closed a month ago. I plan to tell my mortgage lender but wondering if a change in the family needs will help.