VParker -
This website should help - for Fulton county https://www.fultoncountytaxes.org/fultoniwr/05_depts_our_off…
the primary counties in "metro" Atlanta are Fulton, Cobb, Dekalb
The calculation varies (of course) if you are in an incorporated or unincorporated area of each county.
For example, two "new" cities were just created in North Fulton - John's Creek and Milton -
Feel free ot get in touch directly if you have specific areas and I can get you that information.
Otherwise, you can just search for the county/city and tax assessment rate.

Vparker,

It looks like you may be an out of state investor. Be aware that owner/occupied property receives a tax break (homestead exemption). So if you are looking to purchase a property that is currently owner occupied you'll need to make sure of the proper calculation for investment.

You probably already noticed that the metro area of Atlanta covers a number of counties. If you're looking for the city of Atlanta proper, it could be Fulton, Dekalb or both (for example, my sister lives in Candler Park area & pays taxes to two places as I understand it). Just in case it's not complicated enough, each county & city within the county has its own tax structure. The only place I've found online that links through to all the metro county tax stuff is http://www.atlantacommunities.com/information-taxes.php - I don't know how accurate or current it is (I'm just a consumer, not a real estate pro) - but the things I looked up for my own research purposes were accurate.