If you live in a city in Hall County, your property tax bill could drop next year depending on what happens in in the next few days. Working to avoid double taxing city residents, Hall County and its municipalities are this week voting on a service delivery agreement and differential tax rates for residents of Gainesville, Buford, Clermont, Flowery Branch, Gillsville, Lula and Oakwood. Because the county government and city governments sometimes offer the same services — planning and zoning, engineering, road maintenance and code enforcement are the major examples — state law requires the governments to decide how to deliver those services without double dipping into taxpayers’ pockets.