The major tax duty of the assessor-collector, is the assessment (calculation) of taxes on each property in the county and collection of that tax, but the tax assessor-collector does not appraise property.  That function is performed by the Appraisal District, which is not a part of county government.     As an agent of the Texas Department of Transportation, the assessor-collector also is responsible for the registration and licensing of motor vehicles owned by residents of the county.

In most Texas counties, the tax assessor-collector is thef voter registrar.  In a few counties, the county clerk or an elections administrator provide this function. The county tax office voter registration responsibilities include accepting applications for voter registration, issuing voter certificates, maintaining voter registration lists, verifying petitions for local option elections and submitting required reports to the Secretary of State's Office.

The county tax assessor-collector is also responsible for the collections of special fees imposed by the county and state on coin-operated vending machines, alcoholic beverage permits and registration and titling boats.

As with all elected county officials, the tax assessor-collector has ultimate authority over the operations of the office, including the authority to hire and fire personnel and direct their daily activities.  The tax assessor-collector also has authority to determine how to use all other resources allocated to the office during the budget process.