SEA1 will reshape county tax base: home deductions, credits and assessment drivers explained

At a special Delaware County Council meeting Aug. 18, Policy Analytics summarized the state's 2025 property tax reforms (referred to in the presentation as SEA1) and the implications for county revenues and tax bills.

Jason O'Neal explained two central homeowner relief mechanisms in SEA1: a ramp-up of the homestead deduction to roughly two-thirds of assessed value by 2031 and a supplemental homestead credit that reduces liability by 10% up to $300. "A deduction reduces the amount of assessed value that is subject to the tax rate... then on top of that, whatever that remainder is, you're going to get another credit on top of that," O'Neal told the council. He emphasized these are phased policies and that the net effect on county receipts depends on assessed-value changes and how quickly deductions and credits phase in.

O'Neal also walked the council through recent assessment-process changes, including the variable economic multiplier removal and revised cost tables that have magnified assessed-value growth for residential and non-residential parcels. Those administrative changes, combined with market trends, explain much of the rapid assessed-value increases the county has seen in recent cycles.