The average Jeffco home lost 1 percent of its value during the two-year period that ended June 30, 2010, according to an analysis of 149,000 homes by the county assessor.
Notices of valuation went out to homeowners May 1.
Median values are down nearly everywhere across the county as follows: South Jeffco, minus 1.2 percent; Lakewood, minus 1.2 percent; and Golden, minus 1.4 percent.
The exception to declining value and lower tax bills will be homeowners who made significant improvements or additions. They are likely to see increases in actual value.