Anton Vacek (Vacek) appeals from the district court’s judgment of dismissal of his Federal Tort Claims Act (Act) claim for lack of subject matter jurisdiction. We have jurisdiction over this appeal pursuant to 28 U.S.C. § 1291 . We affirm.

I

On March 9, 1999, Vacek was injured when his employer’s truck, in which he was a passenger, was struck by a United States Postal Service (USPS) truck. His workers’ compensation claim was processed by Golden Eagle Insurance Company, his employer’s insurance company and the co-appellant in this case.

Vacek retained Harold Truett as his attorney. According to Truett’s declaration, Truett telephoned the USPS in late July 2000 to determine how to proceed with Vacek’s claim. He was told to complete a Standard Form 95 and to mail it to True-dell Griffin in the Customer Service Department in San Francisco. Truett alleges that he received a Form 95 soon after his telephone call, and that he mailed a completed copy of it to Griffin on August 7, 2000.

On August 16, 2000, Truett received a letter from the USPS containing instructions on how to fill out the Form 95. Truett responded one week later: “A properly completed claim form SF95 was mailed to you a couple weeks back, has not been returned, and I assume has been accepted by the USPS. If this is incorrect, kindly advise.” Truett declared that he enclosed another copy of the Form 95 with this letter, although there is no indication from the letter itself that he did so.

After this letter, Truett did not contact the USPS for over a year. In the meantime, on March 9, 2001, the statute of limitations expired on Vacek’s claim.

On September 28, 2001, Truett wrote to Griffin and offered to settle Vacek’s claim for $75,000. After not receiving a response, Truett wrote three more letters to USPS. Still not having received a response, Truett filed suit against the United States in the district court in April 2002.

On February 5, 2004, the United States moved to dismiss Vacek’s suit for lack of subject matter jurisdiction. The United States argued that Vacek had failed to exhaust administrative remedies, as required by the Act, see 28 U.S.C. §§ 2401 (b), 2675(a), because the USPS had never received his completed Form 95. In support of the motion to dismiss, the United States submitted declarations from Griffin and from Kathleen Arndt, an attorney with the USPS legal department. These declarations stated that the USPS had no record of ever receiving Vacek’s claim.

In opposition, Vacek submitted Truett’s declaration, which stated that Truett had prepared and mailed the Form 95 on August 7, 2000. Truett also presented evidence that he had created a mailing envelope on that day, and that his secretary had made a notation that the complaint was filed.

The district court dismissed the claim for lack of subject matter jurisdiction. The court held that Vacek had “not carried his burden with respect to [proving] receipt” of the form. The court also held that the September 2001 settlement offer did not fulfill the administrative exhaustion *1250 requirement because it was sent after the statute of limitations had expired. In response to Vacek’s argument that the USPS should have been on notice of the claim, the court stated that “the jurisdictional requirements of the administrative exhaustion provisions are not subject to equitable tolling.”

II

We review the district court’s judgment of dismissal for lack of subject matter jurisdiction de novo. Bramwell v. U.S. Bureau of Prisons, 348 F.3d 804, 806 (9th Cir.2003). We also review the district court’s interpretation of the Act de novo. Lehman v. United States, 154 F.3d 1010, 1013 (9th Cir.1998).

A

Kokkonen v. Guardian Life Ins. Co. of Am., 511 U.S. 375, 377 , 114 S.Ct. 1673 , 128 L.Ed.2d 391 (1994) (citations omitted).

Sovereign immunity is an important limitation on the subject matter jurisdiction of federal courts. The United States, as sovereign, can only be sued to the extent it has waived its sovereign immunity. See, e.g., Dep’t of the Army v. Blue Fox, Inc., 525 U.S. 255, 260 , 119 S.Ct. 687 , 142 L.Ed.2d 718 (1999). The Supreme Court has “frequently held ... that a waiver of sovereign immunity is to be strictly construed, in terms of its scope, in favor of the sovereign.” Id. at 261 , 119 S.Ct. 687 .

The Act “waives the sovereign immunity of the United States for certain torts committed by federal employees ‘under circumstances where the United States, if a private person, would be liable to the claimant in accordance with the law of the place where the act or omission occurred.’ ” Smith v. United States, 507 U.S. 197, 201 , 113 S.Ct. 1178 , 122 L.Ed.2d 548 (1993) (emphasis omitted), quoting 28 U.S.C. § 1346 (b). The Act provides that an “action shall not be instituted upon a claim against the United States for money damages” unless the claimant has first exhausted administrative remedies. 28 U.S.C. § 2675 (a).

We have repeatedly held that the exhaustion requirement is jurisdictional in nature and must be interpreted strictly:

Jerves v. United States, 966 F.2d 517, 521 (9th Cir.1992) (internal quotations and citations omitted); see also Cadwalder v. United States, 45 F.3d 297, 300 (9th Cir.1995). We are not allowed to proceed in the absence of fulfillment of the conditions merely because dismissal would visit a harsh result upon the plaintiff. See United States v. Kubrick, 444 U.S. 111, 117-18 , 100 S.Ct. 352 , 62 L.Ed.2d 259 (1979). With regard to the exhaustion requirement, the Supreme Court has stated that “in the long run, experience teaches that strict adherence to the procedural requirements specified by the legislature is the best guarantee of even-handed administration of the law.” McNeil v. United States, *1251 508 U.S. 106, 113 , 113 S.Ct. 1980 , 124 L.Ed.2d 21 (1993), quoting Mohasco Corp. v. Silver, 447 U.S. 807, 826 , 100 S.Ct. 2486 , 65 L.Ed.2d 532 (1980).

B

Federal regulations appear to control this appeal. 28 C.F.R. § 14.2 governs the question of when an administrative, claim is presented for purposes of the Act. It states: “a claim shall be deemed to have been presented when a Federal agency receives from a claimant ... an executed Standard Form 95 or other written.notification of an incident....” Id. (emphasis added). Similarly, 39 C.F.R. § 912.5 , which governs damage arising out of the operation of the USPS, maintains, that “a claim shall be deemed to have been presented when the U.S. Postal Service receives from a claimant ... an executed Standard Form 95 ... or other written notification of an incident....” Id.

In spite of the clear language of the regulation, Vacek relies on Schikore v. BankAmerica Supp. Ret. Plan, 269 F.3d 956, 961 (9th Cir.2001), to contend that the mailbox rule should apply to claims under the Act. The common law mailbox rule provides that the proper and timely mailing of a document creates a “rebuttable presumption that the document has been received by the addressee.... ” Id. However, Schikore involved ERISA claims and has nothing to do with the waiver of sovereign immunity; thus, it is inapplicable to this case. ■

In any event, Vacek’s argument is foreclosed by Bailey v. United States, 642 F.2d 344 (9th Cir.1981). There, the plaintiffs decedent was killed in an explosion on a United States Air Force field. Two coworkers were also injured in the same explosion. The same law firm represented the co-workers and Bailey’s heirs in a suit against the United States for negligence. Id. at 345 . The law firm filed the necessary claim papers for the injured co-workers first, and the claims officer in- charge promptly sent acknowledgments of receipt. Id. In the meantime several letters passed between the law firm and the Air Force regarding the Bailey claim, containing detailed information about the claim that was to be filed, including Bailey’s funeral bills. Id. at 346 . The claims officer replied that the file would be complete once Bailey’s administrative claim was received.

Bailey’s attorneys mailed the claim forms on September 13, 1976. Upon learning in June 1977 that one of the coworker’s claims was denied, the lawyers inquired about Bailey’s claim and were told that there was no record that the Air Forcé had ever received it. The attorneys immediately sent copies of the claim, but the Air Force refused to consider it because it was not filed within two years of the accident. Id. For the purposes of the appeal, the' government accepted that the claim form had been mailed. Id. In the district' court, the government presented the affidavits of four claims officers stating that they had never received the claim. The district court dismissed the action for lack of subject matter jurisdiction. Id.

, We affirmed., ,“[T]he claim was not ‘presented,’ i.e., ‘received’ by the agency, as the statute and the regulation require, within two years. Yet Bailey ... would have us read an exception into the statute and the regulations because of the particular circumstances in this case.” Id. at 346-47 . We continued: “[W]e reject appellant’s claim for relief from the requirements of the Act.... Nor do we accept appellants’ invitation to rewrite the Act and in effect repeal the regulation by holding that mailing alone is sufficient to meet the requirement that a claim be ‘presented.’ ” Id. at 347 .

Our opinion then continued to a specific discussion' of the mailbox rule. • “Finally, *1252 we reject appellants’ claim that a presumption of receipt arises in this case. Assuming, without deciding, that such a presumption may arise under federal law, it was amply rebutted by the affidavits presented to the district court by the government.” Id.

Bailey presents virtually identical facts to the case at hand. As in Bailey , Vacek’s counsel did not send the form by certified mail. As in Bailey , there was a long series of communications between plaintiffs counsel and the administrative agency. As in Bailey , Vacek’s counsel did nothing to verify that the claim had been received. As in Bailey , the government provided affidavits attesting that the claim was never received. There is no principled distinction that can be drawn. Bailey controls this appeal.

C

In light of the Supreme Court’s repeated admonition that waivers of sovereign immunity must be interpreted strictly, we conclude that Bailey sets out the correct rule of law. Since Bailey , virtually every circuit to have ruled on the issue has held that the mailbox rule does not apply to Act claims, regardless of whether it might apply to other federal common law claims. See, e.g., Moya v. United States, 35 F.3d 501, 504 (10th Cir.1994) (“It is the plaintiffs burden to establish the proper agency’s receipt of the request for reconsideration”); Bellecourt v. United States, 994 F.2d 427, 430 (8th Cir.1993) (upholding dismissal where “the ‘request for administrative remedy’ was not mailed by certified mail [and] the ‘request for administrative remedy’ was not received by the Federal Bureau of Prisons”); Drazan v. United States, 762 F.2d 56, 58 (7th Cir.1985) (“[T]he district court was quite right to hold that mailing is not presenting; there must be receipt”). Put simply, it cannot be strict construction of the waiver to read the word “received” as actually meaning “mailed.”

There is only one circuit case to have interpreted the Act to allow the mailbox rule. Barnett v. Okeechobee Hosp., 283 F.3d 1232, 1238-39 (11th Cir.2002). There, Barnett asserted that he had mailed a completed Form 95 and included in his amended complaint a copy of the form, the accompanying cover letter, and a copy of the envelope in which he mailed it. Id. at 1238 . The court found that this evidence “raise[d] an inference” that he had mailed the documents. Id. The court then detailed the acceptance of the mailbox rule and stated that the government had a financial stake in the outcome of this litigation. Id. at 1240 . The court then concluded: “[W]e simply believe that the VA should not be accorded any special presumption of believability because it is a branch of the United States government and should be treated no differently than a private defendant....” Id.

Unlike the court in Barnett , we can think of at least one reason why the federal government should be treated differently from a private defendant in this situation: the federal government must waive sovereign immunity. “In analyzing whether Congress has waived the immunity of the United States, [courts] must construe waivers strictly in favor of the sovereign, and not enlarge the waiver beyond what the language requires.” Library of Congress v. Shaw, 478 U.S. 310, 318 , 106 S.Ct. 2957 , 92 L.Ed.2d 250 (1986) (internal quotation marks and citations omitted). Because Barnett is contrary to the law of the Supreme Court, to our circuit, and to that of three other circuits, we will not follow it.

It would have taken minimal effort on the part of Vacek’s attorney to verify that the claim had been received: sending it by certified mail. Furthermore, the administrative exhaustion requirement is satisfied if the administrative agency fails to make *1253 final disposition of a claim within six months. 28 U.S.C. § 2675 (a). If Vacek’s attorney had contacted the USPS six months after he first mailed the form rather than waiting for over a year, he still would have been within the statute of limitations and could have filed the claim anew. “We do not think that we should now stretch and distort the statute and the regulation to rescue counsel from their own carelessness.” Bailey, 642 F.2d at 347 .

Although neither party cited Bailey in the briefs, Vacek’s counsel conceded Bailey’s controlling effect at oral argument, calling it “a killer case for the government.” He continued, “I recall sitting and reading the dissent and hoping that would become the rule of the circuit.” As a three-judge panel of the circuit, we have no such power. See Barapind v. Enomoto, 400 F.3d 744 , 751 n. 8 (9th Cir.2005) (en banc) (per curiam). Nor do we think Bailey was wrongly decided. Bailey directly controls.

D

Vacek further argues that mail carriers are representatives and mailboxes are extensions of the USPS, such that depositing a letter with either one satisfies the presentment requirement. Vacek did not raise this argument in the district court and, therefore, we will not address it. See Singleton v. Wulff, 428 U.S. 106, 120 , 96 S.Ct. 2868 , 49 L.Ed.2d 826 (1976).

E

Finally, Vacek argues that the USPS should be estopped from arguing that it never received Vacek’s Form 95, because it does not deny receiving multiple letters explicitly mentioning the form.

Vacek’s argument is foreclosed by our caselaw. The United States may assert “the insufficiency of [an] administrative claim under section 2675(a)” at any time because “[t]he government may not be equitably barred from asserting jurisdictional requirements.” Burns v. United States, 764 F.2d 722, 724 (9th Cir.1985); see also Claremont Aircraft, Inc. v. United States, 420 F.2d 896, 898 (9th Cir.1969) (“[Ojrdinary principles of estoppel or waiver are not applied against the Government”). Furthermore, the requirements of the Act are “jurisdictional in nature and may not be waived.” Blain v. United States, 552 F.2d 289, 291 (9th Cir.1977).

AFFIRMED.