The Napa County Mosquito Abatement District is a California Independent Special District funded primarily by a combination of ad valorem property taxes, a benefit assessment, and contracts. 

Ad valorem taxes consists mostly of property taxes secured (buildings and land), property taxes unsecured (planes, boats, etc.), and supplemental property taxes (changes due to new construction or ownership). Ad valorem property taxes make up approximately 55% of the District’s total annual revenues.

The benefit assessment is an annual levy on all non-exempt parcels within the District’s service area. Initial implementation of the assessment required a minimum of 66.7% of the votes cast by property owners be in favor in order to pass and then be levied. The District’s assessment passed with 67.8% of the votes and was certified on July 9, 2003. Benefit assessment revenues make up approximately 43% of the District’s annual revenues.

Government and special district properties are exempt from paying the ad valorem tax and benefit assessment. Some of these properties (e.g. tidal marshes, seasonal wetlands, storm water management systems, waste water ponds, etc.) require significant expenditure of District resources for vector management. The District provides contract services to parcels that are exempt from paying the ad valorem property tax and benefit assessment. Revenues received from these contracts helps defray part of the District’s vector management costs associated with these exempt parcels. Contract revenues make up approximately 1.8% of the District’s annual revenues.

The remaining 0.2% of annual revenues typically consists of interest received on deposited funds and sale of old equipment that has been retired from service.

The District prepares an annual budget of proposed revenues and expenses. Independent annual financial audits of District assets are also performed by certified public accountants, and actuarial studies concerning the District’s long-term financial commitments are completed by licensed actuaries.