What can a buyer do if the seller claimed a rental unit was vacant but a tenant was still living there?

If a seller represented that a unit was vacant when it was not, and you relied on that in deciding to proceed with the purchase, you may have a claim for misrepresentation or breach of the Agreement of Purchase and Sale, depending on exactly what was represented and how, whether in the listing, the agreement itself, or written correspondence. What you can pursue depends heavily on the specific documentation of what the seller actually said and when.

Practical options can range from renegotiating price or terms to reflect the reality of a tenanted property, to pursuing damages for costs caused by the misrepresentation, to, in more serious cases, exploring whether the deal can be unwound entirely. Because you are now dealing with an occupied unit governed by the Residential Tenancies Act, 2006 rather than the vacant property you expected, act quickly: gather any written communications where the seller described the unit as vacant, and speak with your lawyer immediately, since your options and their strength depend on catching this before closing wherever possible.