Reese, Judge.The State Road and Tollway Authority (“SRTA”) filed an action against Catrina Bodamer in the Superior Court of Cobb County to recover $69 in unpaid highway tolls, plus related administrative fees of $3,450 and civil penalties of $9,660, as determined by a final administrative decision. SRTA additionally sought interest so that the total alleged due as of the date of the complaint was in excess of $15,000. Bodamer counterclaimed, alleging lack of notice of the administrative action and toll fines, and seeking judicial review of the administrative decision under the Georgia Administrative Procedure Act (“APA”), OCGA § 50-13-1 et seq.SRTA filed a motion to dismiss the counterclaim, arguing, inter alia, that the superior court lacked jurisdiction to conduct a judicial review because the counterclaim was not timely filed within 30 days of the service of OSAH’s final order. The court denied the motion, and we granted SRTA’s application for interlocutory appeal. On appeal, SRTA argues, for the first time, that Bodamer’s counterclaim is barred by sovereign immunity. For the reasons set forth, infra, we vacate the judgment and remand for further proceedings.The record on appeal does not include a transcript of the hearing on SRTA’s motion to dismiss. “The burden is on the party alleging error to show it affirmatively by the record and when the burden is not met, the judgment complained of is assumed to be correct and must be affirmed. . . . In addition, without a transcript, we must accept the trial court’s findings of fact to the extent they appear to be based on the hearing below.”[1]These findings of fact included the following:[SRTA] alleges [Bodamer] failed to pay the toll on Georgia Highway 400 on [138] occasions between October 2012 and May 2013. Following the alleged violations, SRTA mailed [Bodamer] various Toll Violation Notices to [Bodamer's] address as listed with the Motor Vehicle Division records at the Georgia Department of Revenue. The Notices were sent using United States regular mail and requested payment of each $.50 toll plus an administrative fee of $25.00 for each alleged violation. On November 20, 2013, SRTA issued a Final Notice to [Bodamer] at [her] address of record. The Final Notice was sent using United States regular mail and requested payment of the outstanding tolls and administrative fees in the amount of $3,519.00 by December 20, 2013.Further, according to the trial court’s order:[Bodamer] contends that [she] was not residing at the residence as listed with the Georgia Motor Vehicle Division at the time of the mailing of the Toll Violation Notices or the Final Notice. Accordingly, there is no evidence [Bodamer] actually received any Toll Violation Notices or any other notice seeking payment of outstanding tolls. [Bodamer] contends and [SRTA] acknowledges that it does not have proof of any actual receipt of notice by [Bodamer], i.e., certified mail or personal service. At some point prior to October 2014, SRTA moved for a summary determination in the Office of State Administrative Hearings (“OSAH”) to find [Bodamer] liable for the alleged outstanding fines. Notice of the Administrative Hearing was sent to [Bodamer] via United States regular mail to the same address as prior notices. It is undisputed that [Bodamer] did not appear at the administrative hearing. On October 8, 2014, OSAH entered its Final Decision, based partially on [Bodamer's] failure to respond [to] the motion for summary determination[.]In OSAH’s final decision, attached to SRTA’s complaint, OSAH found Bodamer liable for the alleged unpaid tolls, as well as administrative fees and civil penalties in an amount totaling $13,179 ($3,519 for unpaid tolls and administrative fees plus $9,660 for a civil monetary penalty). The final decision attached to the complaint did not include any proof of prior service of the decision.In her counterclaim, Bodamer sought judicial review of the October 2014 OSAH final decision under OCGA § 50-13-19 (b), which is part of the APA and governs proceedings for review of final “agency” decisions.[2] Under that provision, “[p]roceedings for review are instituted by filing a petition within 30 days after the service of the final decision of the agency[.]“[3] Thus, Bodamer contends, the State has waived sovereign immunity in cases that fall within the APA.[4]The trial court denied SRTA’s motion to dismiss Bodamer’s counterclaim, and this Court granted SRTA’s application for interlocutory review.1. On appeal, SRTA argues that the counterclaim is barred by sovereign immunity and that the superior court erred when it ruled that SRTA was subject to the APA.(a) As an initial matter, Bodamer contends that SRTA waived its argument that her counterclaim is barred by sovereign immunity. We agree with SRTA that sovereign immunity is jurisdictional in nature and that it did not waive this issue by failing to raise it in its motion to dismiss.[5](b) SRTA contends that, “in order to assert a claim against SRTA, Bodamer was required to establish a waiver of SRTA’s sovereign immunity and to bring her claim within that specific waiver.” SRTA argues, however, that “the only basis Bodamer cited for her counterclaim was the APA, which does not waive SRTA’s sovereign immunity[.]” Specifically, SRTA asserts that the APA only applies to the final decisions of “ agencies,” and that, as a “public authority,”[6] SRTA is statutorily exempt from the APA. SRTA argues that, as a public authority,[7] it is not considered an “agency” under the APA, which defines “[a]gency” to exclude “all public authorities except as otherwise expressly provided by law[.]“[8] Bodamer responds that, once SRTA referred the matter to OSAH,[9] the administrative proceedings became subject to the APA.[10] SRTA replies, in part, that “SRTA [did] not have a ‘choice’ to handle the toll violations within SRTA itself or refer the matter to OSAH.” SRTA thus contends that it “is clearly not contracting with OSAH on a case-by-case basis[[11]] under the APA or OSAH Article.”[12]The sovereign immunity issue in this case appears to be one of first impression, and one that requires further development of the record. On consideration of such a defense, “the trial court may hear evidence and make relevant factual findings to decide the threshold issue.”[13]We therefore vacate the judgment and remand this case for further consideration of the applicability of sovereign immunity.[14]2. In light of the foregoing, we do not address SRTA’s remaining claims of error.Judgment vacated and case remanded. Miller, P. J., and Rickman, J., concur.