I think that @MinhT1 may be making some assumption here without know if those assumptions are correct. If you lived in one of the two units as your primary residence, then what @MinhT1 says is spot on correct. However, if you did not live in one of the two units as your primary residence, more information needs to be provided in order to provide you the correct information.
- Were both units "available for rent" in 2021?
- Did you acquire the property in 2021? If so, how? You purchased it? Inherited it? Were gifted it?
- Maybe you only had one unit rented because the other unit was having major work done on it with the intention of renting it out as soon as possible once that work was/is completed?
- You say that only one unit was rented "the full year". Maybe the other unit was rented part of the year?
Details can make a huge difference here.
