How to appeal a denied claim for out-of-network / surprise billing.
When the plan denies a claim as out-of-network, the appeal letter is built around the federal No Surprises Act at 42 U.S.C. § 300gg-19 (45 C.F.R. § 149.110 implementing regulations) and the controlling state balance-billing and network-adequacy statute — not around the EOB’s “non-participating provider” rationale. The right framework varies by clinical context: emergency and post-stabilization care get the strongest federal protections, non-emergent OON disputes route through the ACA external-review channel under 45 C.F.R. § 147.136 or the ERISA § 503 procedure at 29 C.F.R. § 2560.503-1 depending on plan type.
01 · What this segment looks like
An out-of-network or balance-billing denial — and the frameworks that apply to it.
The out-of-network / surprise-billing segment captures claims the plan has adjudicated as non-participating or non-network, in three recognisable shapes: emergency services rendered at an out-of-network facility or by an out-of-network clinician (the federal No Surprises Act is the headline authority, with 42 U.S.C. § 300gg-19 and 45 C.F.R. § 149.110 setting in-network cost-sharing and barring balance billing), post-stabilization care where the plan issues a coverage denial after the patient has stabilized (the same protections attach where the transferring facility or specialist is OON), and non-emergent OON disputes where no in-network provider with the requisite specialty was reasonably available (the appeal is a network-adequacy dispute, framed under the controlling state network-adequacy / balance-billing statute or, for ACA and self-funded plans, under 45 C.F.R. § 147.136 or 29 C.F.R. § 2560.503-1).
The appeal frameworks that apply vary by plan type and by clinical context. ACA marketplace plans pick up the appeals regime at 45 C.F.R. § 147.136 — internal appeal under (b)(2), four-month external review window under (d), expedited review under (b)(3). Self-funded ERISA plans adopt the same federal regime under 29 C.F.R. § 2560.503-1, the implementing regulation for ERISA § 503 — the right to the claims file under (m), the requirement that the plan name its clinical experts under (j)(4), and the pre-service urgent-claim timeframe under (f)(2). Fully-insured plans layer the controlling state balance-billing and network-adequacy statute on top of the federal framework — Texas (Tex. Ins. Code §§ 1457.051, 1457.052), New York (N.Y. Ins. Law § 3241(a), Finance Law § 605), California (Cal. Code Regs. tit. 28 § 1300.67.2; Cal. Health & Safety Code § 1371.30), Illinois (215 ILCS 5/356z.4a) — and those state regimes are typically the more protective of the two when the OON service was non-emergent but no qualified in-network specialist was reasonably available.
A well-built out-of-network appeal letter cites the No Surprises Act framework on the controlling facts (emergency, post-stabilization, or non-emergent network-adequacy dispute), attaches the provider-directory entry and the appointment-access documentation that proves the in-network-alternative gap, and frames the patient-cost-share demand against the in-network equivalent so the reprocessing ask is concrete — in-network cost-sharing under 42 U.S.C. § 300gg-19, the IRO / state external-review channel under 45 C.F.R. § 147.136(d), or the network-adequacy statute in the controlling jurisdiction. The letter branches on whether the request is filed pre- (urgent care where the patient is mid-treatment) or post-denial (the EOB is in hand, the carrier has set OON cost-share).
The three OON / surprise-billing shapes we see most
- 01
Emergency or post-stabilization care at an OON facility
ER admission, urgent imaging or interventional procedure, or labor-and-delivery care at a non-participating facility, or specialty consultation by an OON physician (radiology, pathology, anesthesiology, neonatology) at an otherwise in-network hospital. The federal No Surprises Act at 42 U.S.C. § 300gg-19 and 45 C.F.R. § 149.110 cap patient cost-share at in-network levels and bar balance billing by the non-participating provider, regardless of how the plan has adjudicated the claim on the EOB. The appeal frames the reprocessing ask around in-network cost-share — not around whether the underlying service was covered.
- 02
Non-emergent OON where no in-network specialist was reasonably available
Specialty care (surgical oncology, pediatric subspecialty, complex rheumatology, transplant evaluation) where the plan’s directory shows no in-network provider with the requisite specialty within the plan’s geographic and appointment-access standards. The dispute is a network-adequacy dispute, not a coverage denial. The appeal cites the controlling state network-adequacy statute (Tex. Ins. Code § 1457.052 in TX, N.Y. Ins. Law § 3241(a) in NY, Cal. Code Regs. tit. 28 § 1300.67.2 in CA), attaches the directory lookup and the appointment-access record, and asks for reprocessing at in-network cost-share or a single-case agreement.
- 03
Provider-side balance billing above the plan’s OON reimbursement — common in emergency and anesthesia settings when the non-participating provider has not signed the plan’s assignment and forwards the residual to the patient. The federal No Surprises Act and the parallel state balance-billing statutes bar this balance billing in the emergency, post-stabilization, and certain ancillary-physician contexts; the appeal cites 42 U.S.C. § 300gg-19, references the controlling state statute, and asks for an IDR-eligible determination letter that the patient can hand the provider.
Balance-billed after the carrier paid the OON claim at “usual and customary”
02 · Frequently asked
The No Surprises Act, ERISA, ACA, and state balance-billing frameworks that apply to an OON denial.
Three questions a member typically has before drafting an out-of-network / surprise-billing appeal — with the specific federal regulation and the right of review attached to each answer.
03 · Submit the out-of-network denial
The EOB reprocessed, with the in-network cost-share demanded in the same letter.
Upload the EOB or denial letter, answer the four short intake questions, and Denvow picks the No Surprises Act framework under 42 U.S.C. § 300gg-19 or the network-adequacy statute in the controlling jurisdiction — and the letter branches on whether you’re at the first-stage internal appeal or the second-stage external review.
Already in the intake? Pre-selected to “out-of-network” as the Segment-Denial-Reason — answer the rest and submit.
Other denial-reason pages
Denvow is template-and-tooling, not legal counsel. For denials that genuinely need litigation, an ERISA fiduciary complaint, or a state-court remedy, we recommend a licensed attorney in the relevant jurisdiction — and will say so when we see one.