House Hack Tax Question

[Thomas Barrick]

Hey all!

I purchased a duplex in May of 2015. I lived in one unit and rented out the other unit until Aug of 2018.

I plan to sell the property within the next 2 months and should likely met $50k-$70k due to appreciation in the area.

As I have lived in one unit for 2 of the last 5 years as a primary residence, am I exempt from taxes on the gain?

My CPA said I would owe a prorated amount due to only occupying one unit.

Hoping for some additional input! Thank you!!

-Tommy