O.C.G.A. § 48-3-15

Upon the trial of the action provided for in Code Section 48-3-13 or 48-3-14, which shall be without a jury unless a written demand for jury trial is filed in the case by either party, the respondent may take issue with the sufficiency in law, in fact, or both, of the petition including, but not limited to, jurisdiction over the person of the respondent. The respondent also may attack the tax execution involved in the petition in the manner of an affidavit of illegality and bond as provided by law.