The Municipal Property Assessment Corporation (MPAC) is Ontario's property assessment authority, responsible for valuing all properties in the province for taxation purposes. MPAC is an independent, not-for-profit corporation funded by municipalities through requisitions. Using mass appraisal techniques, MPAC determines current value assessments for approximately five million properties. Property owners receive assessment notices and can request reconsideration or appeal values they believe incorrect. Other provinces have different assessment structures, with some using provincial government agencies and others assigning assessment to municipalities. MPAC assessments directly affect property tax bills since taxes are calculated by applying mill rates to assessed values.