What is a fax appeal, and why is fax still used in 2026?

By Aman, Founder, Apellica. Last reviewed 2026-05-22.

A fax appeal is a formal written request to your health-insurance carrier, sent over fax, asking them to reverse a denied claim. Fax is still used because carrier claim-processing systems were built around fax intake, and a transmission receipt is one of the few low-cost ways a patient can prove the carrier received the document.

When a health insurer denies a claim, the explanation-of-benefits letter or denial notice always tells you how to appeal. For most large carriers in 2026, fax is one of three accepted channels (the other two are postal mail and the secure member portal). Calling member services and asking is not an appeal. Sending an email is usually not accepted. Faxing is.

Inside the carrier, the fax does not arrive at a person. It arrives at a document scanner that turns the pages into PDFs and routes them into the appeals-intake queue by case number or member ID. This is why the cover sheet matters: the scanner indexes off the visible header fields. If the cover sheet does not name the member ID and the claim number, the document drops into a manual-review pile and is read days or weeks later, often after the deadline has passed.

Fax persists because of three structural reasons. First, HIPAA. A fax to a number on file with the carrier is treated as point-to-point transmission under 45 CFR 164.530(c) and is one of the few common channels that legally support PHI delivery without additional encryption setup. Second, evidentiary value. The transmission receipt printed by your fax machine or emailed by your online fax service is a tamper-resistant timestamp that holds up in state DOI complaints and external review. Third, infrastructure inertia. Carrier claim-processing pipelines were architected in the late 1990s. Replacing fax intake would mean rebuilding the appeals-routing engine.

All of that said, fax is not magic. A fax with no cover sheet still gets lost. A fax to the wrong number is treated as never sent. A fax received after the deadline is rejected for timeliness, even if it arrived only minutes late. The mechanics are unforgiving in a way that secure portals (which usually surface deadlines and missing fields before submit) are not.

If reading this is already too much: Apellica handles fax-and-everything-else appeals end to end. see how Apellica files appeals.