Here's the info from Dekalb County on freezing tax assessments:
Jen Bowman, Broker Associate, Realtor
Assessd values are going up as the tax base shrinks due to foreclosures and vacancies - they are essentially jamming the folks paying taxes to make up shortfalls....
In this market, it's common for assessed value to be higher than market value. Keep in mind as well that many times ratios are used by assessors - 40% of market, 50%....and a factor is applied to determine taxes.
hope this helps