Tax liens jump the queue
Everywhere else in real estate, priority follows the recording date: first in time, first in right. Unpaid ad valorem taxes are the great exception. Georgia rule: tax liens arise when the taxes become due and unpaid and are superior to all other liens, to be paid before any other debt, lien or claim of any kind. A first mortgage recorded years earlier still waits behind the county.
So the order is taxes first, then the remaining liens by their own priority. Among tax liens themselves: state, county, special tax district, then municipal. Unpaid taxes are a lien on the specific parcel, not merely a personal debt, and a mechanic's lien does not outrank them.
The 45-day appeal window
A taxpayer may appeal on grounds of value, uniformity, taxability or denial of homestead, filing with the board of tax assessors, with the board of equalization as the default forum, within 45 days of the date on the annual assessment notice.
The 45 days runs from the notice date, not from the day you received it in the mail. You cannot sue directly in superior court within 30 days — superior court comes only after a board of equalization decision, and then within 30 days. And you cannot wait for the tax bill; the window runs from the assessment notice.
Redeeming after a tax sale
Unpaid taxes lead to a public tax sale, and the tax deed is redeemable. The redemption price is the sale price, plus taxes and special assessments the purchaser paid, plus a premium of 20% of the price for the first year or any fraction of it, then 10% of the price for each later year or fraction.
Worked example
Sold at tax sale for $50,000; the purchaser paid $1,200 in taxes; the owner redeems at month nine. $50,000 + $1,200 + (0.20 × $50,000 = $10,000) = $61,200. Dropping the premium gives $51,200; dropping the $1,200 gives $60,000. The figure $66,200 belongs to a second-year redemption, which adds a further 10% ($5,000).