TaxDrift Scoring Methodology
The TaxDrift Index (0–100) quantifies forward-looking property tax millage pressure by modeling overlapping civic debt issuance, CAD assessment lag, and operating budget deficits.
The Composite Scoring Equation
1. Debt Burden Velocity (40%): Total overlapping county, municipal, and ISD bond debt per capita divided by median household income, normalized via sigmoidal transformation.
2. Assessment Lag Spread (35%): Ratio of certified County Assessor (CAD) taxable valuations to the FHFA House Price Index (HPI) repeat-sales benchmark.
3. Operating Deficit CAGR (25%): 3-year compound annual growth rate of municipal operating expenditures relative to local tax revenue growth.
Public Data Repositories & Ingestion
Annual Survey of State and Local Government Finances (IndU GovFin files covering long-term debt and revenues).
Official bond disclosures, voter-approved authorization schedules, and credit ratings for local taxing entities.
FHFA County-Level HPI paired with state Department of Revenue certified property appraisal rolls.