The tax year is the 12-month period for which property taxes are calculated and billed. Most Canadian municipalities use the calendar year (January-December) as the property tax year, aligning with municipal fiscal years and assessment valuation dates. Property taxes are calculated based on assessed values as of a specific date, applied for the tax year, and collected according to municipal payment schedules. Understanding the tax year matters for proration calculations when properties sell, for timing of assessment appeals, and for budget and tax levy decisions. Some jurisdictions have assessment valuation dates that differ from tax year starts, meaning assessments reflect values from a prior date. Tax year alignment simplifies administration and taxpayer understanding.