RIPPLE, Circuit Judge.

Tracy Bartlett filed a one-count complaint against her former employer, the Internal Revenue Service ("IRS"), in which she alleged that she had been constructively discharged in violation of the Rehabilitation Act, 29 U.S.C. § 701 et seq., and the Americans with Disabilities Act ("ADA"), 42 U.S.C. § 12101 et seq. The IRS moved to dismiss the complaint on the ground that Ms. Bartlett had not lodged her administrative complaint within forty-five days of the incident, as dictated by regulation. Ms. Bartlett urged, however, that the doctrine of equitable tolling applied because she was not apprised of the regulatory deadline and because she was suffering from a mental illness. The parties briefed the motion and also submitted additional documentation in support of their respective positions. The district court granted the IRS's motion to dismiss, and Ms. Bartlett timely appealed. Because Ms. Bartlett has not demonstrated that her circumstances warrant equitable tolling, we affirm the judgment of the district court.

I

BACKGROUND

Ms. Bartlett was a long-time employee of the IRS who, in 2009, was absent periodically from work due to her diagnosis with, and treatment for, severe depression.1 On April 22, 2010, Ms. Bartlett was separated from her employment as a result of her inability to return to the workplace.

Following her separation from the IRS, Ms. Bartlett filed a one-count complaint in district court, in which she alleged that she had been constructively discharged on account of her disability in violation of the Rehabilitation Act and the ADA. The IRS responded by filing a motion to dismiss on the ground that Ms. Bartlett had failed to contact an Equal Employment Opportunity ("EEO") Counselor within forty-five days of her allegedly discriminatory separation, as required by 29 C.F.R. § 1614.105(a) (2013).2 In its motion, the IRS also noted that, although the forty-five-day time limit was subject to equitable tolling, in order "`[t]o qualify for [equitable tolling], a complainant must allege and prove, at the least, not only that he had no reason to be aware of his employer's improper motivation when the putative violation occurred, but also that the employer actively misled him and that he relied on the (mis)conduct to his detriment.'"3 The IRS claimed that, "[i]n light of Plaintiff's letter dated April 9, 2010 — before her separation — in which she accused management of creating a hostile work environment, Plaintiff cannot show that she was unaware of the IRS's alleged improper motivation."4 The IRS attached to its motion the April 9 letter from Ms. Bartlett, as well as other documentation.

Ms. Bartlett filed an opposition to the motion to dismiss. In it, she noted that, "[p]rior to her separation from employment, [she] had sought to address the issue of what she perceived as [the] failure of the defendant to grant employment related benefits as it related to her medical condition."5 She continued: "On October 8, 2010[,] the plaintiff, through counsel, sent correspondence to the EEOC claiming the defendant had discriminated against her on the basis of her handicap."6 Ms. Bartlett argued that a court may waive or extend "time limits for equitable reasons when a person is prevented from timely filing because of illness or in other appropriate circumstances."7 She claimed that such circumstances were present in her case because: (1) prior to her departure from the IRS, she had notified the IRS "of the specifics of the dispute from her perspective";8 (2) the documents submitted in opposition to the motion, which set forth her diagnosis with, and hospitalization for, severe depression, "clearly established that [she] was significantly impaired by a mental health issue during the relevant time period";9 and (3) "she was never notified of a 45 day time limit for commencing her claim."10 Attached to her opposition were several exhibits, including an affidavit in which she stated that "[n]o one from the defendant ever informed me that I only had forty-five (45) days to file an employment discrimination claim,"11 and other documents demonstrating that she had informed the IRS of the nature of her complaint and that she had been undergoing treatment for depression.12

With the court's permission, the IRS filed a reply brief in support of its motion to dismiss. It noted first that

According to the IRS, the correspondence that Ms. Bartlett had attached to her opposition clearly established that, at least as of two weeks prior to her separation, "she was mentally competent; she could read; she could write (indeed, quite eloquently); and she was able to understand what had happened and the consequences of her decision."14 The IRS also addressed Ms. Bartlett's claim that "she was unaware of the 45-day deadline."15 It stated: "The declaration of Damaris Ouellette attached hereto as Exhibit A, however, establishes that notices of the deadline were posted in Plaintiff's office since before 2010. Therefore, Plaintiff had constructive, if not actual, notice of the 45-day requirement."16 Finally, the IRS argued that, although it was aware, prior to her departure, that Ms. Bartlett believed that she had been the victim of discrimination, it had not been advised within the forty-five-day window, as required by regulation, that she was going to pursue legal remedies.

In an order issued on February 4, 2013, the district court granted the IRS's motion to dismiss. The court observed that Ms. Bartlett had "admit[ted] that she failed to contact an EEO counselor within the mandated 45 days," and, therefore, her claim was barred unless equitable tolling applied.17 The court then evaluated the four grounds on which Ms. Bartlett had argued that the limitations period applicable to her claim should be equitably tolled. First, the court noted that Ms. Bartlett had not alleged facts "show[ing] that her mental illness was so severe that she was unable to engage in the rational thought process and deliberate decision making necessary to pursue legal remedies in a timely fashion."18 Additionally, the district court rejected Ms. Bartlett's contention that the time should be tolled because the IRS failed to inform her of the forty-five-day contact period. The court observed that Ms. Bartlett had not pointed to affirmative misconduct on behalf of the IRS, nor had she alleged that the IRS failed to post the required EEO information — actions that might have warranted equitable tolling. Finally, the court held that the fact that the IRS was on notice of her potential claims did not toll the statute of limitations: "Counsel cites no authority to suggest that the 45-day contact period is excused when defendant is previously put on notice of the nature of an employee's claim."19

Because Ms. Bartlett had not demonstrated that equitable tolling of the administrative filing requirement was warranted, the district court dismissed Ms. Bartlett's complaint. Ms. Bartlett timely appealed.

II

DISCUSSION

A. Requirement of Administrative Exhaustion

Before we turn to the outcome-determinative question — whether the district court properly dismissed Ms. Bartlett's action on the ground that the forty-five-day limitation set by regulation for commencing administrative review of her claim was not tolled — we must place that question in proper analytical and practical context by addressing an antecedent issue: whether Ms. Bartlett was required to exhaust administrative remedies prior to filing an action under the Rehabilitation Act.20 This question is "antecedent" to the tolling issue because the tolling of an administrative filing requirement only becomes an issue if the plaintiff must exhaust administrative remedies before proceeding with a Rehabilitation Act claim.21 This fundamental issue remains an open question in this circuit.

Whether, or, more appropriately, under what circumstances, a plaintiff must exhaust administrative remedies before filing an action under the Rehabilitation Act presents a statutory interpretation question that is grounded in the manner in which Congress provided for a private cause of action under the Rehabilitation Act. The Rehabilitation Act was enacted in 1973, and among its original provisions was a requirement that federal agencies adopt affirmative action plans for handicapped individuals. 29 U.S.C. § 791(b) (often referred to in the case law as section 501 of the Rehabilitation Act).22 Another provision, 29 U.S.C. § 794(a) (often referred to in the case law as section 504 of the Rehabilitation Act),23 prohibited federally funded programs or activities from excluding handicapped individuals from participating in the program, or denying benefits to handicapped individuals, "solely by reason of her or his disability." The statute did not provide a private right of redress for violation of either section. Nevertheless, "all courts that considered the issue found that section 504 established a private cause of action for handicapped persons subjected to discrimination by recipients of federal funds"; however, "a private cause of action founded on handicap discrimination was not recognized upon section 501 as against a federal government employer." Prewitt v. U.S. Postal Serv., 662 F.2d 292, 302 (5th Cir.1981).

Congress remedied this omission in 1978. As the Third Circuit noted in Spence v. Straw, 54 F.3d 196, 199 (3d Cir.1995), however, it did so in a "less than artful manner," by adopting overlapping amendments from the House and the Senate. "The Senate's contribution focused on provision of a new section in the Rehabilitation Act — section 505, codified at 29 U.S.C. § 794a." Id. The new section provided that, with respect to 29 U.S.C. § 791 governing federal employers, "[t]he remedies, procedures, and rights set forth in [Title VII] of the Civil Rights Act of 1964... shall be available" to any aggrieved employee or applicant for employment. 29 U.S.C. § 794a(a)(1).24 The Senate also codified the cause of action — already recognized by most courts — for those aggrieved by providers and recipients of federal assistance. With respect to those claims, "[t]he remedies, procedures, and rights set forth in [T]itle VI of the Civil Rights Act of 1964, 42 U.S.C. § 2000d et seq.," were available to aggrieved parties. 29 U.S.C. § 794a(a)(2).25

The House, however, took a different approach. Because courts had recognized a private cause of action under § 794 (section 504 of the Rehabilitation Act), the House merely "`extended section 504's proscription against handicap discrimination to "any program or activity conducted by an Executive agency or by the United States Postal Service."'" Spence, 54 F.3d at 199 (quoting Prewitt, 662 F.2d at 302).26 As noted by the Fifth Circuit, "[t]he joint House-Senate conference committee could have chosen to eliminate the partial overlap between the two provisions, but instead the conference committee, and subsequently Congress as a whole, chose to pass both provisions, despite the overlap." Prewitt, 662 F.2d at 304. In taking this action, the Fifth Circuit concluded:

Id.

The manner in which Congress amended the Rehabilitation Act, however, created an "apparently incongruent enforcement scheme." Spence, 54 F.3d at 199. According to the terms of the amended Rehabilitation Act, federal agencies could "be sued for violation of either section 501 or 504 of the Act." Id. If a federal employee sues under § 791 (section 501 of the Rehabilitation Act), Title VII's remedies and administrative processes apply. "Thus, a party is barred from suing a federal agency for violation of section 501 [29 U.S.C. § 791] if he or she has failed to exhaust administrative remedies under Title VII." Id. at 200. However, an aggrieved federal employee also may sue for a violation of § 794, which may be redressed through the remedies and procedures set forth in Title VI of the Civil Rights Act, for which exhaustion is not required. See id.27

Although courts have differed slightly in their reasoning, every circuit court to address the issue directly has determined that a federal employee who brings an action under the Rehabilitation Act must exhaust administrative remedies before proceeding to court. See Spence, 54 F.3d at 201 (collecting cases).28

Although district courts within our own circuit similarly have held that exhaustion is required for federal employees,29 and, in at least one case, we have suggested the same,30 we never have addressed directly whether a federal employee seeking redress under the Rehabilitation Act is limited to proceeding under § 791 (section 501 of the Rehabilitation Act) and, if not, whether she must nonetheless exhaust administrative remedies.

We noted this "procedural wrinkle" in Leary v. Dalton, 58 F.3d 748, 751 (1st Cir.1995), in which a federal employee had brought a Rehabilitation Act claim under 29 U.S.C. § 794 (section 504 of the Rehabilitation Act). We stated:

Leary, 58 F.3d at 751-52 (first alteration in original) (emphasis added) (citations omitted).31 Although Leary discussed the difference in causation standards, it did not discuss the disparity in exhaustion requirements; indeed, it made no mention of exhaustion at all.

The court's methodology in Leary counsels that we need not resolve, in the present case, whether federal employees, proceeding exclusively under § 794, must exhaust administrative remedies. Here, when the Government raised in the district court that Ms. Bartlett had not complied with the forty-five-day administrative exhaustion requirement, she never asserted that she was exempt from the exhaustion requirement because it was inapplicable to the provision on which she was resting her claim. At the very least, by failing to raise the issue in the district court, she has forfeited any argument that exhaustion of remedies under the Rehabilitation Act was not required in this case. See Farris v. Shinseki, 660 F.3d 557, 562 n. 5 (1st Cir. 2011) (forgoing a determination of whether the plaintiff was required to exhaust administrative remedies because the issue had not been raised in the district court or briefed on appeal).

B. Equitable Tolling

The central issue raised by Ms. Bartlett's appeal is whether the district court should have equitably tolled the forty-five-day time limit, set by regulation,32 within which she was required to commence the administrative complaint procedure for her allegedly discriminatory constructive discharge. In the context of litigation initiated by federal employees, we have noted that "administrative exhaustion `is a condition to the waiver of sovereign immunity'" and, therefore, "`must be strictly construed.'" Id. at 563 (quoting Irwin v. Dep't of Veterans Affairs, 498 U.S. 89, 94, 111 S.Ct. 453, 112 L.Ed.2d 435 (1990)). It is "[o]nly in exceptional circumstances" that equitable tolling will extend a filing deadline. Id. (internal quotation marks omitted). To this end, "the heavy burden" of "prov[ing] entitlement to equitable relief lies with the complainant." Id.

Generally speaking, "[e]quitable tolling suspends the running of the limitations period `if the plaintiff, in the exercise of reasonable diligence, could not have discovered information essential to [his claim].'" Ortega Candelaria v. Orthobiologics LLC, 661 F.3d 675, 679-80 (1st Cir. 2011) (alteration in original) (quoting Barreto-Barreto v. United States, 551 F.3d 95, 100 (1st Cir.2008)).33 In making a determination whether equitable tolling should apply in the context of a claim brought under the Age Discrimination in Employment Act ("ADEA"), we have instructed that,

Kale v. Combined Ins. Co. of Am., 861 F.2d 746, 753 (1st Cir.1988) (emphasis added) (citations omitted).

If, however, the plaintiff did not have actual knowledge, or if the employer failed to post the required notices, then "[t]he court should also assess any countervailing equities against the plaintiff." Id. (emphasis added). Specifically, the court should ask the following questions:

Id. (citations omitted). "Finally, even if the court finds that the above factors call for equitable tolling, it must then take account of the degree to which delay prejudices the defendant." Id.

1.

Before the district court, Ms. Bartlett maintained that she did not have actual knowledge of the forty-five-day deadline. Her argument was supported by an affidavit, in which she states: "No one from the defendant ever informed me that I only had forty-five (45) days to file an employment discrimination claim."34 As noted above, however, ordinarily there cannot be equitable tolling based on excusable ignorance if the plaintiff had either actual or constructive knowledge of her statutory rights. Kale, 861 F.2d at 753. Although Ms. Bartlett alleged that she lacked actual knowledge of the filing deadline — and supported that allegation by affidavit — she did not challenge the IRS's assertion, supported by the declaration of Damaris Ouellette, that it had complied with the posting requirements.35 Ms. Bartlett, therefore, has not carried her burden of showing a lack of constructive knowledge of the filing requirements.

In her brief before this court, Ms. Bartlett does not contest that the IRS's postings sufficed to establish her constructive knowledge of the filing deadlines. Instead, she maintains that the district court erred when it decided the issue of notice on a motion to dismiss. She argues that we have held that the issue of constructive notice is one of fact that cannot be decided on a motion to dismiss. She relies on Mercado v. Ritz-Carlton San Juan Hotel, Spa & Casino, 410 F.3d 41 (1st Cir.2005), to support her position.

In Mercado, employees filed Title VII administrative charges after the three-hundred-day deadline had passed, and their employer, Ritz-Carlton, moved to dismiss on the ground that the complaints were untimely. In response, the plaintiffs "claimed that Ritz-Carlton was barred from asserting timeliness as a defense because the hotel [had] failed to comply with EEOC regulations requiring employers to post notices advising employees of their legal rights relating to employment discrimination." Id. at 44. We held that "[h]ere, where appellants have asserted that no informational notices were posted and that they had no knowledge of their legal rights until informed by their attorney, they have met the threshold requirements for avoiding dismissal of their Title VII suit." Id. at 48 (footnote omitted).

Ms. Bartlett maintains that Mercado stands for the proposition that, "where the issue of notice is disputed[,] a plaintiff has met the threshold requirements for avoiding dismissal." Appellant's Br. 13. We agree, but that is not what happened here. Ms. Bartlett never has alleged that the IRS failed to post the required notices. Instead, she asserts that an IRS employee never affirmatively informed her of the filing deadline.36 This assertion contests the issue of actual knowledge, but not constructive knowledge.37

Ms. Bartlett also suggests, without explicitly arguing, that the district court's ruling was more akin to summary judgment than to dismissal for failure to state a claim. See Appellant's Br. 14-15. Under the Federal Rules of Civil Procedure, a district court must advise the parties if, in ruling on a motion to dismiss, it is considering materials outside the pleadings:

Fed.R.Civ.P. 12(d). Here, the district court did not formally convert the IRS's motion to dismiss into a motion for summary judgment, despite the fact that the motion was accompanied by other materials.

The district court's failure to convert the motion, however, does not require reversal. We have made it clear that we "do[] not mechanistically enforce the requirement of express notice of a district court's intention to convert a Rule 12(b)(6) motion into a motion for summary judgment." Boateng v. InterAmerican Univ., Inc., 210 F.3d 56, 60 (1st Cir.2000). "Instead, we treat any error in failing to give express notice as harmless when the opponent has received the affidavit and materials, has had an opportunity to respond to them, and has not controverted their accuracy." Id. (internal quotation marks omitted). Here, Ms. Bartlett not only responded to the IRS's motion to dismiss, but attached several documents to her response. Furthermore, in her briefing on appeal, Ms. Bartlett does not argue that she was denied an opportunity to respond, nor does she suggest that there are other affidavits or documents that she would have submitted to the district court if she had been given formal notice that the court was converting the IRS's motion to a motion for summary judgment. Consequently, the failure by the district court to formally convert the motion to dismiss into a motion for summary judgment was harmless.38

2.

Ms. Bartlett also maintains that the filing deadline should be tolled because she was suffering from mental illness. We have recognized that mental illness may toll the time to file an administrative claim of discrimination, but only if the plaintiff has "show[n] that the mental disability was so severe that the plaintiff was `[un]able to engage in rational thought and deliberate decision making sufficient to pursue [her] claim alone or through counsel.'" Mélendez-Arroyo v. Cutler-Hammer de P.R. Co., 273 F.3d 30, 37 (1st Cir.2001) (second and third alterations in original) (quoting Nunnally v. MacCausland, 996 F.2d 1, 5 (1st Cir.1993)). In this case, the district court applied this standard and determined that equitable tolling was not appropriate because Ms. Bartlett had not argued that her illness had resulted in the necessary level of incapacity.39

On appeal, Ms. Bartlett does not maintain that her illness rendered her unable to engage in rational thought and deliberate decision making. Indeed, she explicitly alleges in her Complaint that she "performed her duties and responsibilities competently and her disability did not otherwise interfere with her ability to perform her job." R.1 at 2. Nowhere does Ms. Bartlett allege that her mental condition — which she says did not affect her job performance — worsened after her separation from employment. She maintains only that the district court applied the incorrect legal standard in determining whether the time limit should be tolled based on mental illness. She argues that our case law "does not stand for the proposition that in an equitable tolling analysis a mental illness must be so severe as to deprive the sufferer of the rational thought necessary to protect their legal rights." Appellant's Br. 14. Rather, she claims that the standard we articulated in Lopez v. Citibank, 808 F.2d 905 (1st Cir.1987) — a case — law antecedent to Mélendez-Arroyo — "is a very narrow one" and is based on the unique facts that were before the court. Appellant's Br. 14.

We do not believe that the district court's determination runs afoul of Lopez. In Lopez, the plaintiff filed his Title VII action eighteen months after he had been notified that the EEOC had dismissed his charge, approximately fifteen months after the ninety-day statute of limitations had run. The plaintiff maintained, however, that equitable tolling should be applied because "he was mentally incapacitated during much or all of the relevant eighteen-month period." Lopez, 808 F.2d at 906. In evaluating this claim, we noted that "there is no absolute rule that would require tolling whenever there is mental disability." Id. We observed that "[t]he federal courts have taken a uniformly narrow view of equitable exceptions to Title VII limitations periods." Id. (internal quotation marks omitted).40 We concluded:

Id. at 907.

We agree with Ms. Bartlett that, in Lopez, the fact that the plaintiff had retained counsel factored into our analysis. However, nothing in Lopez suggests a more relaxed standard for assessing mental incapacity in the context of equitable tolling. See id. at 906. Moreover, since Lopez, we have said:

Mélendez-Arroyo, 273 F.3d at 37 (emphasis added). In Mélendez-Arroyo, we made it "clear that merely to establish a diagnosis such as severe depression is not enough." Id. at 38. Instead, a plaintiff must show that she is, because of her disability, "[un]able to engage in rational thought and deliberate decision making sufficient to pursue [her] claim alone or through counsel." Id. at 37 (alterations in original) (quoting Nunnally, 996 F.2d at 5); see also Miller v. Runyon, 77 F.3d 189, 191 (7th Cir.1996) (stating "the traditional rule [is] that mental illness tolls a statute of limitations only if the illness in fact prevents the sufferer from managing his affairs and thus from understanding his legal rights and acting upon them").

The documentation that Ms. Bartlett submitted to the district court fell far short of what is necessary to "raise[] a factual dispute about her capacity that could not be resolved solely on the papers." Id. at 38. Ms. Bartlett never averred, nor does any of her evidence point to the conclusion, that her depression deprived her of the ability to engage in rational thought or deliberate decision making. She maintains only that "she was experiencing a severe mental illness," Appellant's Br. 17, but, under our case law, "establish[ing] a diagnosis such as severe depression is not enough," Mélendez-Arroyo, 273 F.3d at 38. Rather, the alleged severe mental illness must be marked by a significantly reduced capacity to make rational decisions. On appeal Ms. Bartlett does not argue that she could come forward with evidence that her depression rendered her unable to "understand[] h[er] legal rights and act[] upon them," Miller, 77 F.3d at 191, but was deprived of the opportunity to do so.41

Because Ms. Bartlett has not alleged that she was mentally incapacitated during the forty-five-day filing period and has not argued that she could come forward with evidence establishing such incapacity, she has not made the necessary showing to establish that equitable tolling should be applied to save her untimely administrative action.

Conclusion

For the reasons set forth above, we affirm the judgment of the district court.

AFFIRMED