OPINION ON REHEARING
Opinion on Rehearing by
Wе grant the motion for rehearing filed by appellant, Mission Consolidated Independent School District (the “District”), vacate and withdraw our previous opinion and judgment dated January 28, 2010, and issue this opinion in its place.
In this accelerated interlocutory appeal, the District challenges the trial court’s denial of a plea to the jurisdiction in favor of appellee, Gloria Garcia. By four issues, *552 which can be properly categorized as three, the District argues that the trial court erred in denying its plea to the jurisdiction because: (1) Garcia failed to present evidence to raise a fact issue in response to its plea based on the absence of jurisdictional facts; (2) Garcia’s lawsuit was not timely filed under the Texas Commission on Human Rights Act (“TCHRA”), see Tex. Lab.Code Ann. § 21.254 (Vernon 2006); and (3) the District is not an “employer” within the context of the TCHRA, and, thus, there is no waiver of sovereign immunity. We affirm in part and reverse and render in part.
I. Background
Initially, this case involved three terminated school-district employees — Garcia, Melinda Sotuyo, and Deborah Medina— who filed separate lawsuits against the District and its superintendent, H.F. “Jackie” Dyer, alleging violations of the TCHRA and various common-law claims.
1
See Mission Consol. Indep. Sch. Dist. v. Garcia,
On further appeal, the supreme court concluded that: (1) the Texas Tort Claims Act’s election-of-remedies provision governs all lawsuits filed against a governmental unit; (2) the employees’ common-law claims against the District and the superintendent were barred by the Texas Tort Claims Act’s election-of-remedies provision; and (3) the Texas Tort Claims Act’s election scheme did not bar the employees’ recovery under the TCHRA “because the Legislature has consented to suits against the government under the TCHRA ... and a suit that is based on the TCHRA is not one brought under the [Texas] Tort Claims Act.”
Garcia,
On remand, the District filed another plea to the jurisdiction 2 contending that:
*553 (1) Garcia failed to present evidence to raise a fact issue in response to its plea based on the absence of jurisdictional facts; (2) Garcia failed to comply with the notice provisions contained in the TCHRA, see Tex. Lab.Code ANN. § 21.254; and (3) the District is not an “employer” within the context of the TCHRA, and, therefore, the trial court lacked subject matter jurisdiction over Garcia’s claims. See id. § 21.002(8) (Vernon Suрp.2009). After a hearing, the trial court denied the District’s plea to the jurisdiction. Thereafter, the District filed a request for findings of fact and conclusions of law. The trial court did not issue any fact findings or conclusions; this accelerated interlocutory appeal ensued. See Tex.R.App. P. 28.1; see also Tex. Civ. Prao. & Rem.Code Ann. §§ 51.014(a)(8) (Vernon 2008), 101.001(3)(B) (Vernon 2005).
II. Standard of Review
A plea to the jurisdiction is a dilatory plea used to defeat a cause of action without regard to whether the claims asserted have merit.
Bland Indep. Sch. Dist. v. Blue,
The plaintiff has the burden to plead facts affirmatively showing that the trial court has jurisdiction.
Tex. Ass’n of Bus. v. Tex. Air Control Bd.,
A trial court’s review of a plea to the jurisdiction challenging the existence of jurisdictional facts mirrors that of a traditional motion for summary judgment.
Miranda,
“In considering this evidence, we ‘take as true all evidence favorable to the nonmovant’ and ‘indulge every reasonable inference and resolve any doubts in the nonmovant’s favor.’ ”
Kirwan,
III. DISCUSSION
A. Whether Garcia Failed to Raise a Fact Issue as to Jurisdictional Facts
In its first issue, the District contends that Garcia presented no evidence to raise a fact issue in resрonse to its plea to the jurisdiction based on the absence of jurisdictional facts. The District argues that it conclusively disproved essential elements of each of Garcia’s causes of action based on the evidence it presented to the trial court. Garcia counters that her pleadings sufficiently invoke the subject matter jurisdiction of the trial court and that the trial court’s denial of the District’s plea to the jurisdiction was proper because the District is attempting to resolve the underlying merits of the case, which is an inappropriate use of a plea to the jurisdiction.
In her original petition, Garcia noted that she first began working for the District in October 1976, and “performed all the duties assigned to her with loyalty, dedication[,] and hard work.” However, on or about February 19, 2003, she was “wrongfully discharged by a management employee of [the District] for illegal and discriminatory reasons, including, but not limited to, participating in an investigation involving another district employee ... and for exercising her protected right to freedom of association.” Garcia further alleged that “she was discriminated against by the Defendant Schоol District due to her race and national origin, namely- — Hispanic/Mexican-American descent, gender — female, and due to her age, 48 (d.o.b. — 06/15/1954)” and that “her termination was part of a larger unwritten plan or scheme of the Defendant School District to discriminate against older Hispanic female employees who were politically associated with persons adverse to the Administration.” Garcia also stated that “there was no legitimate business justification for her termination” because she “had always performed a satisfactory job for the Defеndant during her employment,” that “there was work available and there continues to be work available which [Garcia] could perform,” and that she had fulfilled all statutory prerequisites before filing this action.
In response to Garcia’s original petition, the District filed a plea to the jurisdiction challenging Garcia’s jurisdictional facts. The District argued that the trial court lacked subject matter jurisdiction over Garcia’s discrimination claims because the employee selected to replace Garcia is of the same gender, national origin, and racе and is three years older than Garcia. The District further argued that the trial court did not have subject matter jurisdiction over Garcia’s retaliation claim because she “did not participate in an investigation re *555 lated to a claim brought pursuant to Chapter 21 [of the labor code].”
At the hearing on the District’s plea to the jurisdiction, two affidavits were admitted as part of the District’s evidence. The first affidavit was executed by Rebecca Morrison, the Director of Human Resources for the District, who averred that: (1) she had reviewed Garcia’s employment reсords; (2) Garcia had served as “one of two Community/Home School Liaisons for Veterans Memorial High School”; and (3) the next person hired to fill that position was Zoila Longoria. The second affidavit, executed by Longoria, provided that: (1) Longoria’s birthday is April 14, 1951; (2) she is Hispanic; (3) she is a female; and (4) her national origin is Mexican-American. The District did not present any evidence pertinent to Garcia’s retaliation claim.
1. Applicable Law
The TCHRA prohibits an employer from discharging or in any other way discriminating against an employee because of the employee’s race, color, disability, religion, sex, national origin, or age. Tex. Lab.Code Ann. § 21.051 (Vernon 2006). Specifically, section 21.051 of the labor code provides the following:
An employer commits an unlawful employment practice if because of race, color, disability, religion, sex, national origin, or age the employer:
(1) fails or refuses to hire an individual, discharges an individual, or discriminates in any other manner against an individual in connection with compensation or the terms, conditions, or privileges of employment; or
(2) limits, segregates, or classifies an employee or aрplicant for employment in a manner that would deprive or tend to deprive an individual of any employment opportunity or adversely affect in any other manner the status of an employee.
Id.
The TCHRA also prohibits employers from retaliating or discriminating against an employee who engages in certain protected activities under chapter 21 of the labor code.
Id.
§ 21.055 (Vernon 2006). In enacting the TCHRA, the Legislature intended to correlate state law with federal law with respect to employment discrimination; therefore, we look to federal law in interpreting provisions of the TCHRA.
See M.D. Anderson Hosp. & Tumor Inst. v. Willrich,
In order to properly invoke the TCHRA’s limited waiver of governmental immunity, Garcia must have shown a pri-ma facie case of discrimination or retaliation as provided under that statute.
See
Tex. Lab.Code Ann. § 21.051. Accordingly, the trial court’s subject matter jurisdiction will be defeated if the District can conclusively negate any element of Garcia’s pri-ma facie case of discrimination under the TCHRA.
See Miranda,
2. Analysis
a. Age Discrimination
To establish a prima facie case of age discrimination, a plaintiff must show:
*556
(1) that she was discharged; (2) that she was qualified for the position; (3) that she was in the protected class at the time of her discharge; and (4) that she was replaced by someone outside the protectеd class or by someone younger, or otherwise show that she was discharged because of age.
Tex. Dep’t of Cmty. Affairs v. Burdim,
The District submitted evidence that the person next hired to fill Garcia’s position was three years older than Garcia. Garcia did not offer any controverting evidence. The District argues that Garcia failed to create a fact issue that she was replaced by someone outside the protected class or by someone younger and that she, therefore, failed to establish the fourth element of her prima facie case. We agree that Gаrcia did not create a fact issue with regard to her age or Longoria’s age. However, undisputed evidence of the ages of the respective individuals is not, in and of itself, dispositive of Garcia’s claim. Garcia could establish the fourth element of a prima facie age discrimination claim by showing that she was terminated because of her age, regardless of whether she was replaced by someone younger.
See Bienkowski,
In Garcia’s original petition, she alleged she was discriminated against by the District “due to her age” and that “her termination was part of a larger unwritten plan or scheme of the Defendant School District to discriminate against older Hispaniс female employees who were politically associated with persons adverse to the Administration.” The District did not bring forth evidence challenging Garcia’s claim that she was terminated due to her age other than to show that she was replaced by an older employee.
3
Under the applicable law regarding age discrimination claims, that proof was not sufficient to conclusively negate the fourth element of Garcia’s age discrimination claim.
See Miranda,
b. Sex, National Origin and Race Discrimination
To establish a prima facie case of wrongful discharge based on sex, national origin or race discrimination, Garcia was required to show that: (1) she is a member of a protected class; (2) she was qualified for the position that she held before being discharged; (3) she was discharged; and (4) her employer filled the position with a person who is not a member of the protected class.
Raggs v. Miss. Power & Light Co.,
c. Retaliation
Section 21.055 of the labor code establishes that an employer commits an unlawful employment practice if the employer retaliates or discriminates against a person who files a charge of discrimination.
See
Tex. Labor Code Ann. § 21.055
*558
(Vernon 2006). In an action arising under chapter 21 of the labor code, the plaintiff must first make a prima facie showing that: (1) she engаged in a protected activity; (2) an adverse employment action occurred, and (3) a causal link existed between the protected activity and the adverse action.
Dias v. Goodman Mfg. Co., L.P.,
In her original petition, Garcia alleged that she suffered retaliation in the form of wrongful discharge for “participating in an investigation involving another district employee, namely Mona Parras[,] and for exercising her protected right to freedom of association.” The District claims that Garcia’s pleadings are insufficient to confer jurisdiction on the court because she merely alleged participation in “an investigation.” According to the District, “this is not enough because the investigation that is at issue must be one that is brought under Texas Labor Code Chаpter 21.” See id. The District further claims on appeal that Garcia “judicially admitted that the only Chapter 21 investigation that is related to her case was her own claim with the Texas Commission on Human Rights” which she initiated on October 10, 2003, almost eight months after her termination. It argues that “it is logically impossible that she was terminated because of something that happened 8 months after her termination.”
We agree with the District that the protected activity at issue must fall within the scope of chapter 21.
See id.
(prefacing list of protected activities with “under this chapter”);
Dias,
B. Whether Garcia Complied With Labor Code Section 21.254
By its second issue, the District asserts that Garcia failed to comply with the mandatory and jurisdictional notice requirements contained in the TCHRA. See Tex. Lab.Code Ann. § 21.254. Garcia contends that she filed suit within the sixty-day deadline imposed by the TCHRA and that she exercised due diligence in serving the District with notice of her lawsuit.
The TCHRA provides that an employee must file suit within sixty days of receiving a right-to-sue letter from the civil rights division of the Texas Workforce Commission.
See
Tex. Lab.Code Ann. § 21.254. Although the Texas Supreme Court has
*559
not directly addressed whether this sixty-day filing period is jurisdictional, the Court recently concluded that a different TCHRA provision, allowing a two-year period for a complainant to file suit after initially making the complaint,
see id.
§ 22.256 (Vernon 2006), is “mandatory but not jurisdictional.”
In re United Servs. Auto. Ass’n,
The same reasoning holds here. Section 21.254 does not explicitly say that failure to comply with the sixty-day deadline for a complainant to file suit after receiving a right-to-sue letter compels dismissal of the complainant’s suit or deprives the trial court of jurisdiction. See Tex. Lab.Code Ann. § 21.254. 7 We therefore conclude that the sixty-day filing period contained in section 21.254 of the TCHRA is mandatory but not jurisdictional. Accordingly, the trial court did not err in denying the District’s plea to thе jurisdiction on this basis. 8 The District’s second issue is overruled.
*560 C. Whether the District is an “Employer” Under Labor Code Chapter 21
In its third issue, the District argues that it is not subject to the waiver of immunity contained in chapter 21 of the labor code because it is a school district and not an “employer.” See Tex. Lab.Code Ann. § 21.002(8).
The Texas Supreme Court held that immunity is waived as to a school district under chapter 21 of the labor code.
See Garcia,
We first note that the “law of the case” doctrine requires that “questions of law decided on appeal to a court of last resort will govern the case throughout its subsequent stages.”
Hudson v. Wakefield,
The District argues that
Garcia
is not the “law of the case” because the specific issue of whether a school district is immune under the TCHRA was never fully briefed or argued. It further argues that the supreme court’s more recent decision in
Hams County Hospital District v. Tomball Regional Hospital
calls
Garcia
into question.
See
*561 IV. Conclusion
We affirm the judgment of the trial court in part and reverse and render in part as stated in this opinion.
Notes
. Garcia filed her original petition on July 2, 2004, asserting wrongful termination, defamation, negligent misrepresentation, and fraudulent misrepresentation claims. Sotuyo and Medina are not parties to this appeal. Garcia acknowledges on appeal that Dyer was dismissed from the underlying suit.
. We are compelled to note that the District's jurisdictional complaints raised in the plea to the jurisdiction at bar could have been raised in the initial plea to the jurisdiction filed in 2004. While there appears to be no prohibition on such a piecemeal approach, this practice should be discouraged because of the inevitable delay and additional expense.
See
Tex. Civ. Prac. & Rem.Code Ann. § 10.001(1) (Vernon 2002) (providing, among other things, that “[tjhe signing of a pleading or motion ... constitutes a certificate by the signatory that to the signatory’s best knowledge, information, and belief, formed after reasonable inquiry ... the pleading or motion is not being presented for any improper purpose, including to harаss or
to cause unnecessary delay or needless increase in the cost of litigation
... ") (emphasis added);
see also Columbia Med. Ctr. of Las Colinas, Inc. v. Hogue,
. We note that if the District also provided an affidavit or deposition testimony by the appropriate District personnel attesting that Garcia was not "otherwise ... discharged because of age,” that would have been sufficient to negate Garcia's prima facie age discrimination claim.
See Bienkowski v. Am. Airlines,
. A plaintiff may also prove a prima facie case of sex and national origin or race discrimination by showing that: (1) she is a member of a protected class; (2) she was qualified for her position; and (3) persons outside of the class were treated more favorably.
Johnson v. Hoechst Celanese Corp.,
. The fourth element of a prima facie sex, national origin or race discrimination claim can only be satisfied with a showing that the plaintiff was replaced by а person who is not a member of the protected class.
See Raggs,
. The Court also noted that, in
Dubai Petroleum Co.
v.
Kazi,
. Several other courts have directly considered the sixty-day limit provided in section 21.254 and have concluded that the requirement is not jurisdictional.
See Tex. Dep’t of Transp. v. Beckner,
.The District argues that Garcia's alleged failure to notify the District of her suit within the sixty-day filing period deprived the trial court of subject matter jurisdiction, considering section 311.034 of the government code provides that "[statutory prerequisites to a suit, including the prоvision of notice, are jurisdictional requirements in all suits against a governmental entity.” See Tex. Gov’t Code *560 Ann § 311.034 (Vernon Supp.2009). However, the language referenced by the District was not included in the version of section 311.034 that was in effect when Garcia filed suit on July 2, 2004. See Act of June 15, 2001, 77th Leg., R.S., ch. 1158, § 8, 2001 Tex Gen. Laws 2374, 2433 (amended 2005) (current version at Tex. Gov't Code Ann § 311.034). In fact, the predecessor to section 311.034 provided the following:
In order to preserve the legislature’s interest in managing state fiscal matters through the appropriations process, a statute shall not be construed as a waiver of sovereign immunity unless the wаiver is effected by clear and unambiguous language. In a statute, the use of "person" as defined by Section 311.005 to include governmental entities does not indicate legislative intent to waive sovereign immunity unless the context of the statute indicates no other reasonable construction.
Id. Because the predecessor to section 311.034 is silent as to statutory prerequisites and jurisdictional requirements, we are not persuaded by the District's argument.
. "Here, Garcia alleges that the Legislature waived the ISD’s immunity in the TCHRA.”
Garcia,
. We also note that the District, in arguing that it is not an “employer” within thе context of chapter 21 of the labor code, argues that it is neither a "political subdivision” of *561 the State of Texas nor a "state instrumentality.” If this were true, then, in reconciling chapter 21 of the labor code with section 51.014 of the civil practice and remedies code (the statute authorizing certain interlocutory appeals), the District would not be entitled to appeal the trial court’s interlocutory order in this case. Compare Tex Lab.Code Ann § 21.002(8) with Tex. Civ. Prac. & Rem.Code Ann. § 51.014(a)(8) (providing that a governmental unit as defined by section 101.001 of the civil practice and remedies code may appeal from an interlocutory order granting or denying a plea to the jurisdiction); see Tex. Civ. Prac. & Rem Code Ann § 101.001(3)(B) (defining a “[g]overnmental unit" as "a political subdivision of this state including any ... school district ...") (emphasis added).
