Taxes and selling lot with two houses on it - Primary/rental

[Jason Smith]

We purchased the property in 2013 for $49,900. It is a unique lot because on one parcel it has two dwellings. For the purpose of this post, I will call them the front house and back house. We lived in the front house from February 2013 until November 2020. In November 2020 we moved overseas for an international adoption. We rented the front house out during our stay overseas.  In August 2022 we moved back into this front house on our property and have been living in it since then, so a little over a year now. We have never rented the back house because it has been under a complete gut and renovation project that we have slowly worked on since we moved onto the property. We are roughly 3 months away from having this back house complete with an all-in project cost of probably $60k when we finish. 

We are hoping to sell our current property (back house and front house) and move in the next year or two. What are the tax implications of renting this back house out until we sell the property? We don't want to make rental income and lose our shirts on property gains tax. I have looked up a lot of information regarding property gains taxes and house hacking since we would be in a similar situation and have not found anything conclusive to direct us.