A census metropolitan area (CMA) is one or more adjacent municipalities centred on a population centre that has a large number of inhabitants. If you live outside of one of these CMAs, you get a small amount added to your Climate Action Incentive credit. The CRA has more information on the CMAs:
I try to 'tick the box' on line 60102 (and several others), but it will not mark the box. Have tried typing X, typing x, double clicking, right clicking, left clicking. Suggestions?