Maine Medical Center’s (MMC) tax refund suit stalled when the district court found that jurisdictional discovery was not warranted and that without such discovery, MMC could not meet its burden of demonstrating jurisdiction. MMC appealed the district court’s judgment for the government, arguing that it had offered sufficient evidence to merit jurisdictional discovery. Ultimately, MMC did not make an adequate threshold showing that its refund claim was timely filed, and thus the district court ruled that it did not have jurisdiction to hear the case. After careful review, we affirm.
I. Facts & Background
The facts of this case are largely undisputed. As early as August 23, 2004, *112 Maine Medical Center began to look into filing a tax refund claim for reimbursement of taxes paid under the Federal Insurance Contributions Act (FICA) on behalf of its medical residents in 2001. 1 On that date, Kevin Montminy, MMC’s Acting Director of Audit and Compliance Services, discussed the potential refund claim with AI Swallow, MMC’s Associate Vice President of Finance. Over the following months, Montminy continued to monitor and consider the possibility of filing a refund claim for the 2001 FICA taxes.
During a March 16, 2005, conference call, Montminy discussed the FICA refund claim with two accountants from Ernst & Young, Maggie O’Brien and Jeanne Schuster. Then, in early April 2005, Montminy faxed a draft copy of the refund claim to Schuster and Joceyln Bishop, another accountant, noting that the refund request was due on April 15, 2005. On April 6 and 7, Montminy and Schuster emailed each other regarding the specific information needed to complete the refund claim. Ernst & Young’s invoice later referenced “professional tax services rendered through April 15, 2005,” with a specific line-item devoted to researching the 2001 FICA refund claim.
On April 12, 2005, Montminy, Swallow, and two other MMC employees, John Heye, the Vice President of Finance and Treasurer, and Gene Joyner, the Assistant Director of Financial Planning, met to discuss the status of the 2001 FICA refund claim. At the meeting, they decided to file the claim form on April 15. After the meeting, Montminy initiated a series of emails with Jeff Winchenbach, MMC’s Director of Financial Services, in order to obtain necessary details for the refund filing; the email exchange continued until after the close of business on April 14.
At 2:30 PM on April 15, 2005, the day the claim was due, Montminy met with Heye to get the final draft of the claim form approved. Heye signed the form, and Montminy took it back to his office to have his assistant, Debbie Raspiller, prepare it for certified mailing. At 3:22 PM, Raspiller faxed the completed signature page back to Heye for his file.
Montminy’s standard practice then would have been to drive to the main United States Post Office on Forest Avenue in Portland, Maine, and mail the claim via certified mail, return receipt requested. Montminy believes this practice was followed; however, neither he nor anyone else at MMC has a specific memory of completing the mailing, and no one at MMC is aware of the identity of the postal service employee who would have dealt with the mailing of the claim. 2 No one can locate the certified mail receipt or the return receipt. 3 MMC admits that the claim was not mailed for same-day delivery. The Internal Revenue Service (IRS) asserts that it has no record of ever receiving the claim.
On December 30, 2009, MMC filed a refund suit against the government in the United States District Court for the Dis
*113
trict of Maine regarding its 2001, 2002, and 2003 refund claims. The government conceded that the 2002 and 2003 claims were timely filed.
4
However, the government refused to answer interrogatories or provide documents in response to MMC’s discovery requests as they pertained to the 2001 claim,
5
arguing that the claim was not timely filed, and that because timely filing is a jurisdictional prerequisite to a refund suit, the court did not have jurisdiction over the claim. The district court referred the discovery dispute to a magistrate judge. On February 10, 2011, the magistrate issued an order finding that MMC lacked any basis to compel discovery from the IRS, and that without further discovery, MMC could not prove the jurisdictional prerequisite of timely filing of the 2001 claim.
6
See Me. Med. Ctr. v. United States,
II. Discussion
We review legal questions, including those in the tax context, de novo.
Muskat v. United States,
No suit for a tax refund may be maintained in a United States district court “until a claim for a refund ... has been duly filed.” 26 U.S.C. § 7422(a). Thus, timely filing of a refund claim is a jurisdictional prerequisite to a tax refund suit.
Phila. Marine Trade Ass’n v. Comm’r,
Originally, only proof of actual, physical delivery could satisfy a “timely filed” requirement.
See Phila. Marine,
There is, however, yet another means of proving timely filing: in 1954, Congress created a statutory mailbox rule when it enacted § 7502 of the Internal Revenue Code, which allows “[tjimely mailing [to be] treated as timely filing” when certain requirements are met. 26 U.S.C. § 7502. Congress’s purpose, in enacting § 7502, was to “alleviate inequities arising from differences in mail delivery from one part of the country to another.”
Miller,
Section 7502(a) provides in relevant part:
(a) General rule. (1) Date of delivery. If any return, claim, statement, or other document required to be filed, or any payment required to be made, within a prescribed period or on or before a prescribed date under authority of any provision of the internal revenue laws is, after such period or such date, delivered by United States mail to the agency, officer, or office with which such return, claim, statement, or other document is required to be filed, or to which such payment is required to be made, the date of the United States postmark stamped on the cover in which such return, claim, statement, or other document, or payment, is mailed shall be deemed to be the date of delivery or the date of payment, as the case may be.
26 U.S.C. § 7502(a)(1) (emphasis added).
Most courts hold that a taxpayer must show eventual actual delivery, even if it is after the expiration of the statute of limitations, if that taxpayer is to take advantage of the benefits of § 7502(a).
See Phila. Marine,
MMC argues that it need not show actual delivery because it can prove, via extrinsic evidence, that its refund claim had a timely postmark. The Eighth and Ninth Circuits have endorsed this method of satisfying § 7502.
See Anderson v. United States,
MMC’s first problem arises from the fact that circuits that do allow use of extrinsic evidence in a § 7502 context generally do so to invoke the common law mailbox rule. There is a circuit split as to whether extrinsic evidence may be used to meet the timely postmark requirement of § 7502, or whether an actual postmark must be produced. The Second and Sixth Circuits have held that where the taxpayer cannot show an actual postmark and § 7502 is therefore not “literally applicable,” it is inappropriate for a court to accept “testimony or other evidence as proof of actual date of mailing.”
Deutsch v. Comm’r,
MMC’s second problem is that, even if we were to accept the premise that extrinsic evidence is a viable means of proving a postmark for purposes of § 7502,
Wood
and similar cases may be distinguished based on the level of extrinsic proof required. At a minimum, the taxpayers in those cases offered testimony regarding actual mailing and some additional corroborating evidence.
See Lewis,
Here, no one at MMC can remember filing the return, there is no testimony from a postal service employee, and there is no certified mail receipt or return receipt for the mailing transaction, though MMC admits that its standard practice is to send its refund claims by certified mail, return receipt requested. Further, MMC did not attempt to obtain a duplicate receipt from the postal service. There is absolutely no evidence whatsoever of a postmark or actual mailing; instead, there is merely evidence of preparation of the return.
See Me. Med. Ctr.,
MMC’s third problem is that, since the time of the Eighth and Ninth Circuit decisions, the IRS has issued regulations interpreting § 7502 that would appear to foreclose the use of extrinsic evidence as a means of proving a timely postmark. 13 See 26 C.F.R. § 301.7502-1(e) (2011). 14 The regulations lay out a general rule that § 7502 requires actual delivery, 26 C.F.R. § 301.7502 — 1(e)(1), and that the exclusive exceptions to the rule are “proof of proper use of registered or certified mail, and proof of proper use by a duly designated [private delivery service],” id. § 301.7502-1(e)(2). The regulations further emphasize the exclusivity of the exceptions, stating that “[n]o other evidence of a postmark or of mailing will be prima facie evidence of delivery or raise a presumption that the document was delivered.” Id.
The only proof MMC has offered of proper use of certified mail is Montminy’s testimony that his standard practice would have been to send the refund claim via certified mail, return receipt requested. We doubt that this uncorroborated, self-serving testimony is the “proof of proper use of ... certified mail” to which the regulations refer. Id. The rest of the evidence that MMC offers goes to the proper preparation of the return, but not to its mailing in general or the use of certified mail in particular. Thus, under the terms of the regulations, MMC fails to show a timely postmark for purposes of § 7502.
On the evidence presented, MMC did not successfully meet its burden of establishing that its 2001 claim was timely filed. The only remaining question is whether MMC has done enough to compel jurisdictional discovery from the IRS.
As a “district court generally retains broad discretion in determining
*119
whether to grant jurisdictional discovery ... the standard for reversing a district court’s decision to disallow jurisdictional discovery is high,” and the “aggrieved party must show that the lower court’s discovery order was
plainly wrong
and resulted in substantial prejudice.”
Blair v. City of Worcester, 522
F.3d 105, 110-11 (1st Cir.2008) (citing
United States v. Swiss Am. Bank, Ltd.,
In this case, the district court found that MMC was not entitled to jurisdictional discovery because it had failed to make a prima facie showing of proof of timely filing.
Me. Med. Ctr.,
Further, in analyzing a demand for jurisdictional discovery, we have repeatedly emphasized the importance of a plaintiffs diligence.
See Swiss Am. Bank,
While under circumstances like those here presented, the IRS need do nothing more than assert that it has no record of receipt of a tax document in order to dispose of a refund suit, we emphasize that the law encourages parties seeking jurisdictional discovery to exercise more diligence than that shown by MMC.
See Swiss Am. Bank,
III. Conclusion
Even assuming an expansive view of the law that is most favorable to MMC, there is no viable route that leads to proper district court jurisdiction over the 2001 *120 refund claim. Therefore, we affirm the district court’s judgment in favor of the United States.
Notes
. MMC later filed timely tax refund claims for FICA taxes paid in 2002 and 2003, neither of which is at issue on appeal.
. MMC stated at oral argument that it did not question its employees in order to discover if any of them had personal recollection of mailing the 2001 refund claim until about a month before the complaint was filed in December 2009.
. Though the United States Postal Service offers certified mail customers the option of requesting a duplicate return receipt within two years after mailing, MMC admitted at oral argument that it did not avail itself of this service.
. At oral argument, MMC admitted that it received some sort of response from the IRS regarding its 2002 and 2003 claims within a year of their filing, but did not hear from the IRS as to the 2001 claim until after the refund suit was filed, over four years later.
. MMC, in its interrogatories, requested: (1) information pertaining to the time, date, and location of searches by the IRS for its 2001 return, as well as the identity of persons who searched, a description of the search, and the identification of any documents found as a result of the search; (2) a description of how MMC’s tax returns and refund claims since 1996 had been recorded and stored, and if they had been lost or destroyed; (3) the routine steps the IRS took to process FICA refund claims from similar institutions; and (4) the identities of IRS employees or consultants who had studied or analyzed the way that the IRS stores and maintains documents submitted by taxpayers. MMC also requested various documents, including: (1) copies of its tax returns since 2000; (2) documents pertaining to any search by the IRS for MMC's refunds since 1996; (3) documents pertaining to how MMC’s refund claims since 1996 have been stored or indexed; (4) documents describing the IRS’s policies for searching for taxpayer documents; (5) documents pertaining to how the IRS stores or loses taxpayer documents, including recommendations as to how to improve these policies; and (6) documents pertaining to IRS efforts to improve record keeping and record retrieval.
. We refer to this order as the district court decision, though it was initially authored by a magistrate judge.
. On March 12, 2012, while retaining jurisdiction, we remanded this case to the district court for its consideration of whether to issue a Rule 54(b) judgment. See Fed.R.Civ.P. 54(b). The district court entered such a judgment on March 13, 2012, stating that there was no reason to delay the entry of final judgment, and on March 14, 2012, amended its final judgment for the United States to incorporate the Rule 54(b) judgment. The case was thus returned to this court for appellate review.
. There is a split among the circuits as to whether Congress's enactment of 26 U.S.C. § 7502 supplants the common law mailbox rule.
See Sorrentino,
. Section 7502(c) provides in full:
(c) Registered and certified mailing; electronic filing.
(1) Registered mail. For purposes of this section, if any return, claim, statement, or other document, or payment, is sent by United States registered mail
(A) such registration shall be prima facie evidence that the return, claim, statement, or other document was delivered to the agency, officer, or office to which addressed; and
(B) the date of registration shall be deemed the postmark date.
(2) Certified mail; electronic filing. The Secretary is authorized to provide by regulations the extent to which the provisions of paragraph (1) with respect to prima facie evidence of delivery and the postmark date shall apply to certified mail and electronic filing.
26 U.S.C. § 7502(c).
Section 7502(c)(2) thus provides a special rule for certified mail only pursuant to regulations handed down by the Secretary of the Treasury. The relevant regulation, 26 C.F.R. § 301.7502-1(c)(2), specifies that § 7502(c)’s rule can apply to certified mail where "the sender's receipt is postmarked by the postal employee to whom the document or payment is presented.” Therefore, only a taxpayer who can present a receipt may use the certified mail rule under § 7502(c) for prima facie evidence of timely delivery.
. For the first time in its Rule 28(j) letter, the government advanced the argument that there can be no presumption of actual delivery via certified mail where a party never receives its return receipt.
See Moya v. United States,
. The Third Circuit has held that the common law mailbox rule is still available when taxpayers need not make use of § 7502's rule excusing late receipt and instead employ the common law mailbox rule independently. See
Phila. Marine,
. To the extent
Lewis
purported to be following
Anderson
in defining the common law mailbox rule as standing for the proposition that “[p]roper and timely mailing of a document raises the rebuttable presumption that the document has been
timely
received by the addressee,”
Lewis,
. Because the regulations are unnecessary to our holding, we leave to another day the decision of whether we will give them
Chevron
deference.
See Dickow v. United States,
. The regulations were proposed on September 21, 2004, when they were first published in the Federal Register.
See
Timely Mailing Treated as Timely Filing, 69 Fed. Reg. 56,377 (proposed Sept. 21, 2004) (codified at 26 C.F.R. § 301.7502-1). The initial proposed regulations noted that they would be effective for documents mailed after the proposal date.
Id.
at 56,379. This is also made clear in the final regulations.
See
26 C.F.R. § 301.7502-1(g)(4) (2011) (noting that § 301.7502-1(e)(2) applies to "all documents mailed after September 21, 2004.”). Though the regulations did not become final until August 23, 2011,
see
Timely Mailing Treated as Timely Filing, 76 Fed. Reg. 52,561 (Aug. 23, 2011) (final regulations) (codified at 26 C.F.R. § 301.7502-1), the Secretary of the Treasury is expressly authorized by statute to make regulations retroactive to the date of their proposal,
see
26 U.S.C. § 7805(b)(1)(B);
Bowen v. Georgetown Univ. Hosp.,
