MEMORANDUM OPINION

ADELE HEDGES, Chief Justice.

In this tax dispute, Harris County Appraisal District (hereinafter, "HCAD") appeals the summary judgment granted in favor of Shell Oil Co. (hereinafter, "Shell") and the denial of its own cross-motion for summary judgment on the grounds that the trial court erred by: (1) failing to dismiss the suit for lack of subject matter jurisdiction; (2) granting Shell's summary judgment motion on the basis that Harris County, an indispensable party, was not joined in the suit and that Shell waived its foreign-trade zone tax exemption as a matter of law; and (3) denying HCAD's summary judgment motion because Shell failed to prove that it was excused from its obligation to pay ad valorem taxes as agreed with Harris County. We affirm.

Background

On December 15, 1993, the U.S. Department of Commerce Foreign-Trade Zones Board approved the Port of Houston Authority's application, as grantee of Foreign-Trade Zone 84, to establish a special purpose foreign-trade subzone for the Shell refinery and petrochemical complex in Harris County. As part of the application, Shell agreed, subject to two conditions, to forego its right of exemption under the foreign-trade zone laws with regard to Harris County ad valorem taxes for goods that are in the subzone (the "1993 Agreement"). In consideration, Harris County agreed to not oppose the application to create the subzone. After the subzone was established in 1993, HCAD appraised Shell's inventory, and Shell paid ad valorem taxes to Harris County for some years.

For tax year 2004, HCAD sent Shell a notice of appraised value for its inventory with regard to Harris County ad valorem taxes. Shell filed a written protest with the Appraisal Review Board (the "ARB") challenging HCAD's denial of a foreign-trade zone exemption ("the FTZ exemption") from Harris County ad valorem taxes for inventory located in the Shell foreign-trade subzone. After a hearing, the ARB issued its Order Determining Protest in August of 2004, denying the FTZ exemption on Shell's inventory. Thereafter, Shell filed suit to appeal the ARB's order, claiming that it is entitled to the FTZ exemption. In the trial court, Shell moved for summary judgment; HCAD responded and filed a cross-motion for summary judgment. The trial court granted Shell's summary judgment motion, denied HCAD's motion, and ordered that Shell is entitled to exemption under section 11.12 of the Property Tax Code.

Jurisdiction

In its first issue, HCAD contends that the trial court erred in not granting its plea to the jurisdiction. The basis of its plea is that, according to HCAD, this case involves a contract dispute between Shell and Harris County. Because neither HCAD's nor ARB's jurisdiction extends over contract rights disputes, the district court lacked subject matter jurisdiction to hear Shell's appeal from ARB's order.

Shell counters that this case is a tax protest action in which it appealed HCAD's and then ARB's denial of an FTZ exemption for the 2004 tax year. Shell claims that had it not appealed the denial of the requested FTZ exemption as provided by the Tax Code, the 2004 tax rolls would have become final, foreclosing Shell's claim of the exemption for that year based on the exclusive remedies provision in the Tax Code.

Whether a court has subject-matter jurisdiction is a question of law reviewed de novo. Tex. Dep't of Parks Wildlife v. Miranda, 133 S.W.3d 217, 226 (Tex. 2004).

Tax Code Provisions

The Property Tax Code (the "Tax Code") creates appraisal districts and requires each district to appraise property for ad valorem tax purposes of each taxing unit within the district. Tex. Tax Code Ann. § 6.01 (Vernon 2008); Atascosa County v. Atascosa County Appraisal Dist., 990 S.W.2d 255, 257 (Tex. 1999). To discharge this duty, appraisal districts must establish appraisal offices and retain chief appraisers. Atascosa County, 990 S.W.2d at 257; see Tex. Tax Code Ann. § 6.05 (Vernon 2008). The Tax Code also establishes an appraisal review board for each district, which is charged with determining property owners' protests and ensuring that property is properly appraised. See Tex. Tax Code Ann. §§ 6.41, 41.01 (Vernon 2008); Atascosa County, 990 S.W.2d at 257.

A property owner may protest the denial of an exemption and any other action that adversely affects the property owner by filing a timely written notice of protest with ARB. Tex. Tax Code Ann. §§ 41.41, 41.44 (Vernon 2008). ARB then schedules a hearing and issues a written order determining the property owner's challenge. See id. §§ 41.45, 41.46, 41.47 (Vernon 2008); Atascosa County, 990 S.W.2d at 259. A property owner is entitled to appeal an ARB order denying the requested exemption within forty-five days of notice of final order. See Tex. Tax Code Ann. §§ 41.41, 42.01, 42.21(Vernon 2008). Review is by trial de novo, and the district court shall try all issues of fact and law raised by the pleadings in the manner applicable to civil suits generally. Id. § 42.23 (Vernon 2008).

Procedures prescribed by the Property Tax Code for adjudication of the grounds of protest authorized by the Tax Code are exclusive. Id. § 42.09(a) (Vernon 2008); St. Joseph Orthodox Christian Church v. Spring Branch Indep. Sch. Dist., 110 S.W.3d 477, 479 (Tex.App.-Houston [14th Dist.] 2003, no pet.). A property owner may not raise any of those grounds as a defense to a suit to enforce collection of delinquent taxes, or as a basis of a claim for relief in a suit by the property owner to prevent the tax collection process or to obtain a refund on taxes paid. Tex. Tax Code Ann. § 42.09(a); St. Joseph Orthodox Christian Church, 110 S.W.3d at 479. The denial of exemption from property tax constitutes one such ground of protest. St. Joseph Orthodox Christian Church, 110 S.W.3d at 479; see Tex. Tax Code Ann. § 41.41(a)(4). Thus, because the Tax Code prescribes procedures by which a taxpayer asserts a protest, appeals the determination of a protest, and receives any resulting correction and refund, a taxpayer's claim of entitlement to an exemption may not be raised as a later defense. See St. Joseph Orthodox Christian Church, 110 S.W.3d at 479.

Nature of the Dispute

In this case, Shell followed the specifically prescribed Tax Code procedures to protest HCAD's appraisal. It claimed entitlement to an FTZ exemption from Harris County ad valorem taxes pursuant to section 11.12 of the Tax Code. However, HCAD claims that this case is not properly brought under the Tax Code. Rather, HCAD asserts, this case is not a true tax protest action but instead involves a contract dispute between Harris County and Shell. Therefore, it claims, HCAD, ARB, and the district court lacked subject matter jurisdiction under the Tax Code to adjudicate this contract dispute. We disagree.

As discussed in detail above, the Tax Code provides but one opportunity to protest the denial of an exemption and prescribes specific procedures the property owner must follow to that effect. See St. Joseph Orthodox Christian Church, 110 S.W.3d at 479. Thus, filing a common law contract action against Harris County to review the 1993 Agreement and determine the obligations under that agreement would have neither brought relief to Shell nor settled the present dispute. Harris County has no authority to grant Shell the requested FTZ exemption, even if it agreed that Shell is entitled to the exemption based on the 1993 Agreement. More importantly, Shell would have been precluded from claiming the FTZ exemption had it not timely followed the exclusive procedures set out in the Tax Code. See Tex. Tax Code Ann § 42.09(a); St. Joseph Orthodox Christian Church, 110 S.W.3d at 479.

Therefore, we conclude that HCAD miscast this case as a contract dispute improperly brought under the Tax Code. Because Shell properly pursued this tax protest action under the prescribed procedures of the Tax Code, HCAD, ARB, and the district court had jurisdiction to review Shell's protest challenging HCAD's denial of the FTZ exemption. Accordingly, we overrule HCAD's first issue.

Joinder

In its second issue, asserting error in the trial court's denial of its summary judgment, HCAD assails the refusal of the trial court to join Harris County as a party in light of the latter's alleged status as an indispensable party in this contract dispute. HCAD claims that Harris County remains a necessary party and must be joined because the existence and the validity of Shell's FTZ exemption can be determined only by adjudicating the terms and conditions of Shell's 1993 Agreement with Harris County. Further, HCAD asserts that Rule 39 mandates the joinder of Harris County. That rule requires the presence of all persons who have an interest in the litigation to the end that any relief awarded will effectively and completely adjudicate the dispute. See Tex. R. Civ. P. 39.

Having determined that the present case involves a tax protest action, we look to the Tax Code for guidance in addressing HCAD's joinder issue. Section 42.031(b) provides that a taxing unit may not intervene in, or in any other manner be made a party to, an appeal of an order of the ARB determining a taxpayer protest if the appeal was brought by the property owner. Tex. Tax Code Ann. § 42.031(b) (Vernon 2008). The Tax Code thus forecloses the joinder of a taxing unit if a property owner appeals ARB's order determining the property owner's protest. See id.

In this case, Shell appealed ARB's order determining its protest action and denying the requested FTZ exemption. Harris County could not have been joined as a party in the appeal to the district court under section 42.031(b). Accordingly, the trial court did not err in refusing to join Harris County as a party in this case. We overrule HCAD's issue in that respect.

Summary Judgment

In its second issue, HCAD further argues that the trial court erred by granting Shell's summary judgment motion because Shell waived the FTZ exemption as a matter of law. In its third issue, HCAD asserts that the trial court erred by denying its summary judgment motion because Shell failed to meet its burden of proving excuse from its obligation under the 1993 Agreement with Harris County.

Standard of Review

We review summary judgments de novo. Valence Operating Co. v. Dorsett, 164 S.W.3d 656, 661 (Tex. 2005). When, as here, both parties move for summary judgment and the trial court grants one motion and denies the other, the appellate court considers the summary judgment evidence presented by both sides and determines all questions presented. Id. If the reviewing court finds that the trial court erred, the appellate court renders the judgment the trial court should have rendered. Id. On cross-motions for summary judgment, each party bears the burden of establishing that it is entitled to judgment as a matter of law. City of Garland v. Dallas Morning News, 22 S.W.3d 351, 356 (Tex. 2000). In a traditional motion for summary judgment, if the movant's motion and summary judgment evidence facially establish its right to judgment as a matter of law, the burden shifts to the nonmovant to raise a genuine, material fact issue sufficient to defeat summary judgment. M.D. Anderson Hosp. Tumor Inst. v. Willrich, 28 S.W.3d 22, 23 (Tex. 2000).

Analysis

In the trial court, Shell moved for summary judgment claiming that its inventory was exempt from Harris County ad valorem taxes pursuant to section 11.12 of the Tax Code because the inventory qualified for an FTZ exemption under 19 U.S.C.A. § 81o(e). HCAD responded to Shell's motion and cross-moved for summary judgment. According to HCAD, the evidence shows as a matter of law that Shell expressly waived its right to the FTZ exemption in the 1993 Agreement, in which it agreed to forego its right of exemption. HCAD further argued that once the right was waived, Shell could not reclaim it without Harris County's consent. Shell replied that it was entitled to summary judgment because (1) the waiver was expressly conditioned upon preliminary actions by Harris County, (2) HCAD failed to prove that Harris County met either of the two express conditions, and (3) Shell's evidence conclusively showed that Harris County failed to comply with either condition.

On appeal, HCAD argues that the trial court improperly granted Shell's summary judgment motion because, by producing the 1993 Agreement and by producing evidence that Shell honored the waiver from 1993 until 2004, it proved that Shell waived its FTZ exemption as a matter of law. HCAD also claims that the summary judgment record establishes Shell's recognition of the waiver in previous tax years. According to HCAD, because such evidence was sufficient to show Shell's satisfaction that the conditions of the waiver had been met in prior years, the burden shifted to Shell to prove that the conditions were not currently met by Harris County. Lastly, HCAD contends that Shell failed to prove excuse from its obligation under the 1993 Agreement when it failed to show that Harris County did not meet the conditions of the waiver. HCAD alleges that, because the conditions are conditions subsequent excusing Shell's obligations under the 1993 Agreement, it was Shell's burden to establish HCAD's failure to fulfill those conditions.

In response, Shell points to what it characterizes as uncontroverted evidence that (1) Shell met the requirements for an FTZ exemption, and (2) it did not waive the exemption for the 2004 tax year. Shell alleges that it submitted conclusive evidence of Harris County's failure to meet either of the required conditions, while HCAD submitted evidence of Shell's honoring the waiver from only 1993 until 2004.

As stated, because both HCAD and Shell moved for summary judgment, we consider all the summary judgment evidence presented and determine all the questions presented. Dorsett, 164 S.W.3d at 661. The dispute in this case focuses on whether Shell is entitled to an FTZ exemption or whether it has waived its right to exemption under the 1993 Agreement. Waiver is an intentional relinquishment of a known right or intentional conduct inconsistent with that right. Jernigan v. Langley, 111 S.W.3d 153, 156 (Tex. 2003).

The waiver at issue is conditioned upon Harris County's meeting two conditions. The 1993 Agreement provides:

Shell Oil Company agrees that upon activation of its foreign-trade subzone status at its Deer Park Manufacturing Complex, to for[e]go its right of exemption under the Foreign-Trade Zone laws with regard to Harris County ad valorem taxes for goods which are in the subzone for a bona fide Customs reason.

As condition of the above, Harris County agrees to:

(1) Require consistent treatment for Shell with regard to similar industries. If a company in a similar industry is allowed exemption from Harris County ad valorem taxes then Shell will be allowed a similar right of exemption.

(2) Review this agreement every three years in good faith to consider its terms in light of existing circumstances.

The waiver is effective only if Harris County satisfied both conditions.

In order to obtain summary judgment on an affirmative defense, a defendant must conclusively prove all essential elements of that defense. Rhone-Poulenc, Inc. v. Steel, 997 S.W.2d 217, 223 (Tex. 1999); Black v. Victoria Lloyds Ins. Co., 797 S.W.2d 20, 27 (Tex. 1990). To defeat a plaintiff's summary judgment motion, a defendant must only provide summary judgment evidence that raises a fact issue on each element of an affirmative defense. See Brownlee v. Brownlee, 665 S.W.2d 111, 112 (Tex. 1984); Brown v. Aztec Rig Equip., Inc., 921 S.W.2d 835, 845 (Tex.App.-Houston [14th Dist.] 1996, writ denied).

HCAD contends that the summary judgment evidence offered to prove the status of the two conditions is conclusory, irrelevant, and does not support the trial court's ruling. With respect to the first condition, Shell presented Stone Exhibit H ("Exhibit H"), offered in conjunction with the deposition testimony of HCAD employee Charles Stone, and two affidavits from Shell employees Karen Shook and Glenn Jue.

Exhibit H contains a two page list of companies that received FTZ exemptions for the 2004 tax year. This information is confirmed by Stone's deposition in which he testified that Exhibit H "is a list of companies that have received the FTZ exemption." Thus, this evidence shows that the companies listed in Exhibit H have been granted an FTZ exemption from HCAD — the same exemption Shell requested. Additionally, as noted above, HCAD's brief acknowledges that some of the companies listed in Exhibit H are "readily recognizable as petroleum companies" and "all [the companies listed] received the same type of exemption as Shell."

HCAD contends that this evidence did not prove Harris County's failure to meet the first condition. In particular, HCAD alleges that, although Exhibit H is a list of company names, "some readily recognizable as petroleum companies," that shows "all [the companies listed] received the same type of exemption as Shell," the list does not show whether any of these companies were treated more favorably by Harris County than Shell was treated. HCAD also dismisses Shook and Jue's affidavits as conclusory and irrelevant because they suggest only that the companies listed in Exhibit H are similar to Shell but do not address when, whether, or under what terms the companies were treated more favorably than Shell.

We disagree with HCAD's contention that Shook and Jue's affidavits were conclusory and irrelevant. In her affidavit, Shook testified that based on her employment as Feed Stock and Integration manager at Shell Oil Company, she has become familiar with the nature of operations conducted by companies in industries similar to Shell Oil Company's industry. She identified four companies as being similar industries as Shell Oil Company in the year 2004, two of which were listed among the companies found on Exhibit H. Similarly, Jue testified in his affidavit that, based on his employment as Refinery Interface Manager for Shell Chemical LP, he has become familiar with the nature of operations conducted by companies in industries similar to Shell Chemical LP's industry. He named six companies as being similar industries to Shell Chemical LP's industry, five of which were listed on Exhibit H as companies having received the FTZ exemption for tax year 2004. These affidavits are not conclusory because the affiants testified that their statements were based on personal knowledge obtained by virtue of their employment.

Additionally, the affidavits and Exhibit H are not irrelevant simply because they do not address whether Harris County treated the listed companies more favorably than Shell. Under the first condition, "[i]f a company in a similar industry is allowed exemption from Harris County ad valorem taxes then Shell will be allowed a similar right of exemption." An exemption from ad valorem taxes is by its very nature a favorable treatment. According to the waiver, when Harris County grants an FTZ exemption to a company in a similar industry as Shell, Harris County is required to allow Shell an FTZ exemption. Therefore, the evidence shows that all the companies listed in Exhibit H received an FTZ exemption for tax year 2004 and that several of these companies were in a similar industry as Shell. Shell established that Harris County did not meet the first condition of the waiver as a matter of law.

Consequently, the waiver was not effective regardless of whether Shell proved that Harris County met the second condition. Accordingly, we overrule HCAD's second and third issues, concluding that the trial court properly granted Shell's summary judgment motion and denied HCAD's cross-motion for summary judgment. We affirm the judgment of the trial court.