If you purchased a home together and you weren't common-law then you'd claim as single. You will still enter that you purchased a home and co-own it.
If you qualify for the Home Buyers Amount (sometimes referred to as the First-time Home Buyers' Amount) is a tax credit available to first-time home buyers.
For the purposes of this credit, the CRA defines a first-time home buyer as a person who has not lived in another home owned by you or your partner in the year of the acquisition or in any of the four preceding years.
The home doesn't have to be a single-family house to qualify; you can still get the tax credit if you've bought a condo, townhouse, mobile home, or even an apartment. Homes under construction also qualify.
If you qualify then you both can ask for the credit and claim 50% each of the credit unless you decide who will claim it all.