
551 S.E.2d 412 (2001)
250 Ga. App. 310
TRAMMEL
v.
CLAYTON COUNTY BOARD OF EL-10 COMMISSIONERS et al.
Clayton County Board of El-10 Commissioners et al.
v.
Trammel.
Nos. A01A0202, A01A0203.
Court of Appeals of Georgia.
July 2, 2001.
*413 Lee Sexton, Jonesboro, for appellant.
Hancock & Echols, Jack R. Hancock, Forest Park, Brian R. Dempsey, Lilburn, for appellees.
ELDRIDGE, Judge.
James Trammel brought a complaint for declaratory judgment and injunctive relief against the Clayton County Board of Commissioners, individually and in their official capacities, C. Crandle Bray, Richard Reagan, Terry J. Starr, Gerald A. Matthews, and Virginia B. Gray, for a proposed expenditure of tax money to erect a hangar at Tara Field in Henry County. After answering, the defendants moved for summary judgment. On January 3, 2000, the trial court granted the motion for summary judgment for the defendants, which was entered on January 4, 2000. On February 18, 2000, the defendants moved for litigation expenses under OCGA § 9-15-14(a) and (b) within 45 days of final disposition of the case. On May 19, 2000, plaintiff filed his motion for attorney fees under OCGA § 9-15-14 against the defendants for seeking sanctions against him on February 18, 2000; plaintiff's motion was filed more than 45 days after the final disposition of the case contrary to OCGA § 9-15-14. On July 10, 2000, in separate orders, the trial court denied each motion. On August 24, 2000, this Court granted plaintiff's application for discretionary appeal. On August 25, 2000, plaintiff filed his notice of appeal. On August 31, 2000, the defendants cross-appealed.
Case No. A01A0202.
Plaintiff contends the trial court erred in dismissing his request for sanctions under OCGA § 9-15-14 as being untimely filed. We disagree.
Final disposition of this action within the meaning of OCGA § 9-15-14(e) was the entry of final judgment by filing the order granting summary judgment on January 4, 2000, in the trial court. Fairburn Banking Co. v. Gafford, 263 Ga. 792, 439 S.E.2d 482 (1994). Under OCGA §§ 5-6-34(a)(1) and 9-11-56(h), the entry of final judgment granting the total summary judgment constituted a final appealable order from which the 45 days began to run within which to seek sanctions. *414 The 45 day period ended in this case on February 18, 2000. Little v. Gen. Motors Corp., 229 Ga.App. 781, 782, 495 S.E.2d 572 (1997); Gist v. DeKalb Tire Co., 223 Ga.App. 397, 477 S.E.2d 616 (1996).
After the expiration of 45 days without the filing of the motion seeking sanctions, the trial court lost subject matter jurisdiction to consider such post-judgment motion, because the sanction was a matter of limited right under terms and conditions established by the legislature. OCGA § 9-15-14. Therefore, the legislature limited a trial court's jurisdiction to consider such post judgment sanction to motions brought within 45 days after final disposition in the trial court. The 45 day period provided a statutory exception to post-judgment jurisdiction as a limited "window of opportunity" to seek such sanctions, because the trial court was granted power to consider such issues only within such period, which power it lacked absent this legislative grant. When the motion for sanctions "was not filed within [the] window of opportunity, the trial court lacked jurisdiction to consider it." Fairburn Banking Co. v. Gafford, supra at 794, 439 S.E.2d 482. Thus, failure to bring the motion for sanctions within the window of opportunity means that the trial court loses such legislatively limited power to act outside such time period as a matter of subject matter jurisdiction. See Brassfield & Gorrie v. Ogletree, 241 Ga.App. 56, 526 S.E.2d 103 (1999); Hewitt v. Walker, 234 Ga.App. 78, 506 S.E.2d 215 (1998).
This sanction is in derogation of common law, and it must be strictly construed against the movant seeking the benefit of the statute. Browning v. Gaster Lumber Co., 267 Ga. 72, 73, 475 S.E.2d 576 (1996); DeKalb County v. Post Apt. Homes, 234 Ga. App. 409, 410(1), 506 S.E.2d 899 (1998). Thus, final disposition does not mean disposition on appeal or other post-judgment motions, but entry of final judgment in the trial court; otherwise, as in this case, matters could be spun out indefinitely after final disposition by judgment without real finality and closure. See Fairburn Banking Co. v. Gafford, supra at 792, 439 S.E.2d 482; Little v. Gen. Motors Corp., supra at 781, 495 S.E.2d 572; Gist v. DeKalb Tire Co., supra at 397, 477 S.E.2d 616. Therefore, the defendants filing their motion for sanctions under OCGA § 9-15-14 on the forty-fifth day did not extend plaintiff's time to file his own motion for this or subsequent conduct after the expiration of the 45 days. See Hewitt v. Walker, supra at 78, 506 S.E.2d 215. Thus, the trial court properly denied the plaintiff's motion for sanctions as being untimely.
Case No. A01A0203
Defendants cross-appealed and raise several issues regarding the trial court's denial of their motion for sanctions.
The solemn duty devolves upon this court to inquire into its jurisdiction to entertain each appeal and review the alleged errors of the trial court. Byrd v. Goodman, 192 Ga. 466(1), 15 S.E.2d 619 [(1941)]. The jurisdiction of an appellate court to consider an appeal depends upon whether the appeal is taken in substantial compliance with the rules of appellate procedure prescribing the conditions under which the judgment of the trial court may be considered appealable.
Gibson v. Hodges, 221 Ga. 779, 780-781(1), 147 S.E.2d 329 (1966)rev'd on other grounds, Gillen v. Bostick, 234 Ga. 308, 310, 215 S.E.2d 676 (1975). This Court has authority to examine its jurisdiction over an appeal on its own motion and to dismiss the appeal if jurisdiction is lacking. Kirby v. Woods, 212 Ga. 20(1), 90 S.E.2d 4 (1955); Peoples Loan Co. v. Allen, 198 Ga. 516, 518, 32 S.E.2d 175 (1944); Fricks v. Cole, 111 Ga.App. 635, 142 S.E.2d 382 (1965).
For defendants to bring a cross-appeal, this Court must have jurisdiction of the underlying appeal. OCGA § 5-6-38; Wood v. Atkinson, 229 Ga. 179, 180-181, 190 S.E.2d 46 (1972); Ewing Holding Corp. v. Egan Stanley Investments, 154 Ga.App. 493, 496(2), 268 S.E.2d 733 (1980); see also Reliance Ins. Co. v. Cobb County, 235 Ga.App. 685, 686-687, 510 S.E.2d 129 (1998). After February 18, 2000, the trial court could not entertain a subsequently filed motion for sanctions by the plaintiff; the trial court lacked subject matter jurisdiction to hear such post-judgment issues, because the motion *415 for sanctions was filed outside the 45 day window of opportunity. Fairburn Banking Co. v. Gafford, supra at 794, 439 S.E.2d 482.
Under OCGA § 5-6-38(a), a cross-appeal can be brought only where a valid appeal exists. See Buschel v. Kysor/Warren, 213 Ga.App. 91, 93(3), 444 S.E.2d 105 (1994). Absent a cross-appeal status for the lack of jurisdiction in the trial court as to the underlying appeal, defendants' cross-appeal must stand on its own merits as an independent appeal. See OCGA § 5-6-48(e); Burns v. Howard, 239 Ga.App. 315, 317, 520 S.E.2d 491 (1999); Patel v. Ga. Power Co., 234 Ga. App. 141, 142(2), 505 S.E.2d 787 (1998); Roberts v. Pearce, 232 Ga.App. 417, 418, 501 S.E.2d 555 (1998).
The defendants' cross-appeal is based upon the denial of their petition for sanctions, as was the plaintiff's appeal; however, the plaintiff sought and obtained leave to bring a discretionary appeal, where the defendant's did not independently do so. Burns v. Howard, supra at 317, 520 S.E.2d 491; Roberts v. Pearce, supra at 418, 501 S.E.2d 555.
[T]he trial court's denial of defendant[s'] motion ... is not a final appealable judgment within the meaning of [OCGA §§ 5-6-35(a)(1) and (10) ]. Rather, that ruling is subject to the ... application procedures for [discretionary appeal procedure applicable to OCGA § 5-6-35(a)(10) unless the award is appealed as part of an otherwise directly appealable judgment]. Consequently, since the main appeal ... must be dismissed in its entirety, and [the] defendant[s] filed no application under [OCGA § 5-6-35 for discretionary appeal] of the denial of its motion ...., we have no independent jurisdiction over the cross-appeal...., and the same must be dismissed.
(Citations and punctuation omitted.) Patel v. Ga. Power Co., supra at 142, 505 S.E.2d 787; see also Burns v. Howard, supra at 316 317, 520 S.E.2d 491; Roberts v. Pearce, supra at 418, 501 S.E.2d 555.
As such, defendants' appeal would be untimely as an independent appeal; an untimely appeal constitutes a lack of jurisdiction in the appellate court, mandating dismissal. Boney v. State, 236 Ga.App. 179, 180, 510 S.E.2d 892 (1999); Thompkins v. State, 157 Ga.App. 203, 276 S.E.2d 885 (1981). Thus, we dismiss this appeal also for lack of jurisdiction. See Burns v. Howard, supra at 317, 520 S.E.2d 491.
Appeal and cross-appeal dismissed for lack of jurisdiction.
ANDREWS, P.J., concurs in judgment only. MILLER, J., concurs.
