NH HB1380

Replaces fair market value with "replacement or cost-based value" as the standard for property tax assessments in New Hampshire, where buildings are valued at reconstruction cost minus depreciation and land is valued based on preparation costs rather than speculative market prices

Implements a phased transition beginning with December 2026 tax bills using a 50/50 blend of old and new methods, shifting to 25/75 in second-half 2027, and full replacement-value assessment starting in 2028

Requires the Department of Revenue Administration to adopt rules establishing uniform standards, approved cost manuals, depreciation schedules, and land-preparation cost factors for the new assessment methodology

Prohibits municipalities from increasing total property tax levies solely due to the assessment methodology change; any revenue increases must come from separate budgetary actions

Mandates annual reports starting in 2028 to the legislature on taxpayer appeals, changes in assessed values compared to former fair market value, and recommendations for methodology improvements