O.C.G.A. § 48-2-37: Preparation of delinquent returns.

In any case in which any return, report, or other information is not filed or made available to the commissioner as required by law, the commissioner may proceed at the expense of the delinquent taxpayer to ascertain such information in any way which the commissioner reasonably considers proper or appropriate; and the commissioner is authorized to prepare, execute, and file such returns. Any return so made and filed by the commissioner or his agent shall be prima facie correct and sufficient for all legal purposes.