Residents of two heavily populated townships don’t have much longer to appeal the assessments used to calculate property tax bills due next year.

The deadline is Tuesday for Nunda Township property owners, and Friday for owners in Dorr Township. The townships include all or significant parts of Woodstock, Crystal Lake, McHenry, Bull Valley, Prairie Grove, Oakwood Hills and Holiday Hills.

Property owners have 30 days to appeal from the day their township assessments are published. Assessments, or one-third of a property’s value, determine the owner’s share of taxing districts’ extensions for property tax bills due in 2013.