My accountant mentioned filing a joint venture election for our rental property — what does that actually do?

A joint venture election under the Excise Tax Act lets co-venturers in a qualifying joint venture designate one participant as the "operator," who then accounts for GST/HST, charging it, claiming input tax credits, and filing the returns, on behalf of the whole joint venture for the activities covered by the election, instead of every co-owner separately registering, charging tax, and filing their own HST returns on their share of the property's activities.

For a jointly owned rental property, this can significantly simplify the tax administration: tenants and suppliers deal with one operator on GST/HST matters, one HST account handles the property's activities, and the co-venturers don't each need to separately track and remit tax on their proportional share of rent or expenses. The underlying ownership and profit-sharing arrangement between the co-venturers doesn't change, the election only affects who handles the HST mechanics.

Not every joint arrangement qualifies as a "joint venture" for this purpose, and not every activity is eligible even where the arrangement itself does qualify, so the specific structure of your property ownership and operating agreement needs to be checked against the eligibility rules before the election is relied on, rather than assumed to apply just because multiple people co-own the property.