Pleading Primary-Carrier Status in ERISA Coordination-of-Benefits Disputes (and the Limits of Blankenship at the Rule 12(b)(6) Stage)

Case: Dina Mendoza v. Aetna Life Insurance Company
Court: United States Court of Appeals for the Eleventh Circuit
Date: March 19, 2026
Disposition: Affirmed in part; reversed in part; remanded (leave to amend).

1. Introduction

Dina Mendoza sued Aetna Life Insurance Company under ERISA after Aetna denied coverage for $420,269.00 in neonatal ICU-related hospital charges for her newborn twins. Aetna’s stated reason for denial was not a lack of coverage in the abstract, but a coordination-of-benefits determination: Aetna asserted it was the secondary carrier because another plan (the father’s plan) was primary.

Mendoza alleged that the twins were never enrolled in the father’s plan and that his coverage did not apply, making Aetna primary. Her plan (attached to the complaint) contained a COB provision applying the “birthday rule” (the earlier birthday in the calendar year determines the primary plan when a dependent child is covered by both parents).

The district court dismissed the complaint with prejudice under Rule 12(b)(6), concluding Mendoza failed to plausibly allege facts showing Aetna was the primary carrier. On appeal, the Eleventh Circuit agreed the complaint was deficient as pleaded, but held Mendoza should be given an opportunity to amend.

2. Summary of the Opinion

The Eleventh Circuit (per Judge Lagoa) affirmed the Rule 12(b)(6) dismissal because Mendoza did not plead facts making it plausible that Aetna’s primary/secondary determination was wrong. Given the COB “birthday rule” and the acknowledged existence of the father’s plan, the complaint needed factual allegations showing either:

• the father’s plan did not provide coverage for the twins’ post-birth hospital stay (based on the plan’s terms, not merely lack of “enrollment”), or
• the birthday rule did not make the father’s plan primary (e.g., because his birthday fell later in the year).

However, the Court reversed the “with prejudice” aspect and remanded with instructions to allow amendment, emphasizing that the missing facts (the father’s birthdate and the father’s plan terms) were known or readily knowable to Mendoza at filing. The Court also underscored Rule 11’s requirement that counsel conduct a reasonable inquiry before asserting such facts.

Concurring opinions

• Judge Newsom concurred in the judgment but suggested the original complaint was “probably good enough,” because it alleged no other insurance was available and that Aetna denied coverage.
• Judge Kidd concurred in the judgment but argued the district court erred by using the Blankenship framework as a pleading screen; Blankenship is a standard of review applied with an administrative record, not a Rule 12(b)(6) pleading requirement. Judge Kidd would affirm dismissal on different grounds raised by Aetna (including ambiguity as to whether the claim was under ERISA § 502(a)(1)(B) or § 502(a)(3), and insufficient factual content to plausibly allege benefits “due under the terms of the plan”).

3. Analysis

A. Precedents Cited

1) Pleading standards and Rule 12(b)(6)

• Bell Atl. Corp. v. Twombly, 550 U.S. 544, 555, 570 (2007): The majority relies on Twombly’s plausibility requirement—allegations must rise above speculation and plausibly show entitlement to relief. The Court frames Mendoza’s shortfall as the gap between allegations consistent with Aetna’s liability and allegations that make liability plausible in light of the COB provision.
• Ashcroft v. Iqbal, 556 U.S. 662, 678 (2009): Referenced in Judge Kidd’s concurrence to reinforce that standard Rule 8 plausibility governs ERISA pleadings; ERISA does not impose a special requirement to plead the administrator’s decision was “wrong.”
• Crowder v. Delta Air Lines, Inc., 963 F.3d 1197, 1202 (11th Cir. 2020): Cited for the de novo review of a Rule 12(b)(6) dismissal and the requirement to construe allegations in the plaintiff’s favor. The opinion also cites Crowder (at 1203) for plan interpretation: courts look to the plain and ordinary meaning of plan terms.
• Reese v. Ellis, Painter, Ratterree & Adams, LLP, 678 F.3d 1211, 1215-16 (11th Cir. 2012): Used to treat the plan attached to the complaint as part of the pleading for Rule 12(b)(6) purposes, which is crucial here because the COB provision is analyzed directly from the attached plan language.
• Turner v. Williams, 65 F.4th 564, 577 (11th Cir. 2023): Reinforces that allegations “merely consistent” with liability are not enough; they must plausibly establish entitlement to relief. The majority uses Turner to explain why Mendoza’s “no other coverage” statements, without supporting facts about the father’s plan or the birthday rule, do not plausibly show Aetna was primary.

2) ERISA benefit-denial review framework

• Capone v. Aetna Life Ins. Co., 592 F.3d 1189, 1195 (11th Cir. 2010): The majority quotes Capone for the proposition that courts apply de novo review to determine whether a benefits-denial decision is “wrong,” and if not, the inquiry ends. The majority’s pleading analysis effectively asks whether the complaint plausibly alleges that Aetna’s COB determination was wrong.
• Blankenship v. Metropolitan Life Insurance Company, 644 F.3d 1350 (11th Cir. 2011): Central to Judge Kidd’s concurrence. Judge Kidd characterizes Blankenship as a judicial standard of review requiring an administrative record, not a pleading yardstick that a plaintiff must satisfy in a complaint.
• Williamson v. Travelport, LP, 953 F.3d 1278, 1289-90 (11th Cir. 2020): Judge Kidd relies heavily on Williamson to argue that a district court cannot make a step-one Blankenship determination without the administrative record. Williamson is deployed as the doctrinal barrier to transforming ERISA merits review into a Rule 12(b)(6) “wrongness” pleading requirement.

3) ERISA remedial structure: § 502(a)(1)(B) vs § 502(a)(3)

• Jones v. Am. Gen. Life & Accident Ins. Co., 370 F.3d 1065, 1072-73 (11th Cir. 2004) and Katz v. Comprehensive Plan Of Grp. Ins., 197 F.3d 1084, 1088 (11th Cir. 1999): Cited in Judge Kidd’s concurrence for the rule that where a plaintiff has an “adequate remedy” under ERISA § 502(a)(1)(B) (benefits due), she cannot alternatively proceed under ERISA § 502(a)(3) (equitable relief for breach of fiduciary duty) for the same injury. Judge Kidd suggests the complaint should be dismissed (with leave) because it is unclear which ERISA cause of action Mendoza is asserting and because some theories may be foreclosed by the adequate-remedy rule.

4) Rule 11 pleading integrity

• Gulisano v. Burlington, Inc., 34 F.4th 935, 942 (11th Cir. 2022) and Worldwide Primates, Inc. v. McGreal, 87 F.3d 1252, 1255 (11th Cir. 1996): The majority uses these cases to emphasize counsel’s affirmative duty to investigate facts and law before pleading, and the continuing duty not to reaffirm claims once known to lack merit. This is not mere rhetoric: the remand is conditioned on good-faith amendment supported by reasonable inquiry into the father’s plan terms and other readily ascertainable facts (e.g., birthdates).

5) Non-ERISA statutory backdrop

• Fla. Stat. § 627.6575(1): Cited to illustrate that newborn coverage may arise automatically by operation of law in group insurance plans, undercutting a simplistic “not enrolled” theory. The majority uses this to highlight why pleading must focus on coverage availability under the father’s plan, not only on whether the father affirmatively enrolled dependents.

B. Legal Reasoning

1) The majority’s core pleading holding in COB disputes

The majority’s reasoning follows a practical syllogism:

• Mendoza’s own plan (part of the complaint) contains a COB provision, including the birthday rule, that determines primary/secondary status when a child is covered by both parents’ plans.
• Mendoza acknowledges the father has a separate plan.
• Therefore, to plausibly plead wrongful denial (under her asserted theory), the complaint must include facts showing why Aetna’s plan is primary notwithstanding the father’s plan—either because the father’s plan did not cover the twins’ charges at birth (by its terms), or because the birthday rule would not make the father’s plan primary.

The Court deems Mendoza’s allegations about non-enrollment insufficient because COB turns on whether the child has “health coverage under more than one health plan,” not on whether the parents completed paperwork. The opinion also notes that Mendoza’s plan automatically covered newborns for the first 30 days, underscoring that enrollment status and coverage status can diverge.

2) Plan-text primacy and the absence of a newborn-care carveout

Mendoza argued that newborn care coverage was not contingent on COB. The Court rejected that argument by reading the plan as establishing a general COB framework: when Aetna is primary, it pays “first”; when secondary, it pays “after the primary plan.” Citing Crowder, the Court treats the plan’s plain text as controlling and finds no language exempting newborn claims from COB.

3) Procedural posture: dismissal affirmed, but “with prejudice” reversed

Although the Court agreed the complaint was deficient, it emphasized that the missing facts were not uniquely within Aetna’s control. The father’s birthdate and plan terms were “known—or readily knowable” to Mendoza. That reality cuts both ways: it justifies dismissal for implausibility as pleaded, but it also supports a remand to allow amendment because the deficiency is potentially curable without discovery.

4) Rule 11 as a guardrail for amendment

The majority’s remand is coupled with an explicit Rule 11 warning: counsel must investigate the father’s plan terms and relevant facts before pleading them and cannot rely solely on client assurances. The opinion also encourages attaching the father’s plan (if in plaintiff’s possession) to allow evaluation against actual terms.

5) The concurrences expose a doctrinal fault line

Judge Kidd’s concurrence squarely challenges the district court’s (and, implicitly, the majority’s) reliance on an ERISA “wrongness” concept at the pleading stage, invoking Williamson v. Travelport, LP to argue that Blankenship step-one review belongs later—after the administrative record exists. Judge Newsom, by contrast, treats the complaint’s “no other coverage” facts as enough to clear plausibility, and sees remand for amendment as a pragmatic path given the absence of the father’s plan.

C. Impact

1) Practical pleading expectations in COB-driven ERISA benefit disputes

The majority opinion signals that when a plaintiff’s own plan documents (attached to the complaint) disclose a COB provision, and the plaintiff acknowledges another potential plan exists, bare assertions of “no other coverage” may be deemed too conclusory unless supported by factual content addressing:

• coverage availability under the other plan (eligibility, dependent coverage, exclusions, conditions precedent), and/or
• the COB rule’s operation (here, facts such as the parents’ birthdays).

In future cases, plaintiffs’ counsel can expect pressure (and likely motions to dismiss) to plead around COB provisions with particularity tied to plan text—especially where the complaint itself incorporates the plan.

2) Reinforcing that “enrollment” is not always the same as “coverage”

By highlighting automatic newborn coverage (and referencing Florida’s newborn coverage statute), the opinion underscores a recurring insurance concept: dependent coverage can attach by operation of law or plan design even absent formal enrollment. That framing may influence how litigants plead and prove COB disputes involving newborns and other automatically covered dependents.

3) Leave-to-amend as the default remedy for curable plausibility gaps

Even while affirming dismissal, the Court rejects a hard “with prejudice” outcome where missing facts are readily ascertainable and could plausibly cure the defect. This encourages district courts to distinguish between (i) incurable legal defects and (ii) curable factual incompleteness—especially in ERISA cases that often begin without a full record.

4) The unresolved tension: ERISA “wrongness” review vs pleading standards

Judge Kidd’s concurrence (anchored in Williamson v. Travelport, LP) foreshadows future disputes over whether district courts may, at the motion-to-dismiss stage, require a complaint to allege facts demonstrating a denial was “wrong” in a Blankenship sense. Litigants should expect continued briefing on when ERISA merits-review frameworks may be invoked procedurally—and what materials (e.g., the administrative record) must be before the court.

4. Complex Concepts Simplified

• ERISA § 502(a): ERISA’s civil-enforcement provision. In practice, many benefits cases proceed under § 502(a)(1)(B) (to recover benefits due under plan terms). § 502(a)(3) is typically for equitable relief (often breach-of-fiduciary-duty remedies) and may be unavailable if § 502(a)(1)(B) provides an adequate remedy.
• Coordination of Benefits (COB): Contract provisions that prevent double payment when two plans might cover the same person. COB decides which plan pays first (primary) and which pays after (secondary).
• Birthday rule: A common COB rule for dependent children: the parent whose birthday occurs earlier in the calendar year has the primary plan for the child (regardless of birth year).
• Rule 12(b)(6) & plausibility: A motion to dismiss tests the complaint’s factual sufficiency. A plaintiff must plead enough facts to make liability plausible, not merely possible.
• Administrative record: The set of documents and information the plan administrator relied on when deciding a claim. ERISA merits review typically focuses on this record; some judges (see Judge Kidd) view it as essential before applying the Blankenship review framework.
• Rule 11: A certification by attorneys that factual contentions have evidentiary support (or will likely after investigation) and that legal claims are warranted. The opinion uses Rule 11 to caution against pleading key COB facts (like another plan’s coverage terms) without reasonable investigation.

5. Conclusion

The Eleventh Circuit’s decision in Mendoza v. Aetna Life Insurance Company affirms that, where a plaintiff’s own plan includes a COB provision and another potential plan exists, a complaint alleging wrongful denial must do more than assert “no other coverage” or “not enrolled.” The pleading should allege concrete facts showing why the other plan did not provide coverage, or why the COB rule (including the birthday rule) does not render the defendant plan secondary.

At the same time, the Court rejects a punitive “with prejudice” dismissal when the defect is potentially curable with readily obtainable facts—remanding to permit amendment, while imposing a clear Rule 11 expectation of pre-filing factual diligence. The concurrences spotlight a continuing doctrinal debate: whether ERISA merits-review frameworks like Blankenship should influence pleading burdens at all, or only apply later once the administrative record is before the court.