Upcoming Deadlines to Dispute California Property Tax Valuation for 2025

California property owners can file decline-in-value assessment appeals to reduce property taxes if their property's value has dropped since 2020. Deadlines for 2025 appeals vary by county, either September 15 or December 1, with no extensions allowed. Proposition 8 permits reassessment based on January 1, 2025 values for the 2025–2026 tax year. Timely filing is crucial to benefit from potential tax reductions.