Can support arrears follow a payor if they move to another province?

Yes. Moving to another province does not erase a support obligation or the arrears that have built up under it. Canada has reciprocal enforcement arrangements between provinces specifically so that a support order made in one province, including Ontario, can be registered and enforced in the province where the payor now lives, and Ontario's Family Responsibility Office can work with the equivalent enforcement agency elsewhere to pursue collection.

In practice, this usually means the recipient or FRO takes steps to have the order recognized in the new province, after which local enforcement tools in that province become available in addition to, or instead of, Ontario's own mechanisms. The exact process and timing can vary depending on where the payor has moved and how the interprovincial arrangement in question operates, so it isn't something to assume happens instantly or without any action. A recipient dealing with a payor who has relocated should contact FRO to find out what steps are needed to keep enforcement active, and get legal advice if the arrears are significant or the payor appears to be moving specifically to avoid enforcement.