If you are purchasing a home that is currently rented out (or has an apartment that is currently rented out), there are extra precautions that you should take to ensure that the closing will go smoothly, whether you intend to have the tenancies severed on closing or want to keep the tenants.
If you are buying a house that is rented and intend to live there yourself, you need to be certain that the vendor has given proper notice to the tenants to ensure that they will leave on closing. If you want to keep the tenants, you will need tenant acknowledgements of the change in ownership and will want to review the tenancy agreements to ensure that you are content with the way the agreement has been set up. If you intend to retain the tenants for a time but will want to move in yourself eventually, you will also want to review the timelines in the Residential Tenancies Act so that you give proper notice. You will also want to generally review the Act to make sure that you are keeping to the obligations of a residential landlord.
Having tenants can be cost-effective, particularly for first-time buyers, but you should always ensure that you are prepared to work within the rules and obligations of being a landlord.