Glossary
Tiering exception
In one sentence
A request to have a covered drug charged at a cheaper tier's cost sharing. It turns on a prescriber's statement that the preferred drugs would not work as well for you or would harm you.
What tiering exception actually means
This one is about price rather than coverage. The drug is on the formulary and the plan will pay for it; the argument is about which tier it sits in and therefore what you pay at the counter.
The rule puts a specific piece of evidence at the center of it. A prescriber has to say that the preferred alternatives would not be as effective for you, or would have adverse effects for you, or both. That is a narrow pair of statements, and a request that argues something else — convenience, preference, a general view about the drug — is not arguing the thing the rule asks about.
The statement may be given orally, though the plan is allowed to ask for it in writing afterwards.
The text it comes from
This is the wording the definition rests on. Where it decides anything for you, read the section rather than our summary of it.
The prescriber's statement is the hinge, and the rule enumerates what it must say. "A prescribing physician or other prescriber must provide an oral or written supporting statement that the preferred drug(s) for the treatment of the enrollee's condition— (i) Would not be as effective for the enrollee as the requested drug; (ii) Would have adverse effects for the enrollee; or (iii) Both paragraphs (a)(4)(i) and (a)(4)(ii) of this section apply."
42 CFR §423.578(a)(4), Electronic Code of Federal Regulations, effective August 2026 · source
The plan must run the process and must grant where the test is met: a sponsor managing a tiered formulary "must establish and maintain reasonable and complete exceptions procedures subject to CMS' approval," and "grants an exception whenever it determines that the requested non-preferred drug for treatment of the enrollee's condition is medically necessary, consistent with the physician's or other prescriber's statement." The procedures must also "address situations where a formulary's tiering structure changes during the year and an enrollee is using a drug affected by the change."
42 CFR §423.578(a), Electronic Code of Federal Regulations, effective August 2026 · source
Where this comes from
- 42 CFR §423.578(a)(4), Electronic Code of Federal Regulations, effective August 2026 — www.ecfr.gov/current/title-42/part-423/section-423.578
Where this comes up
American GLP is not a law firm, an insurer, a government office or a clinician, and nothing here is legal or medical advice. This page says what a published rule means by a word. Which rulebook governs you depends on your plan, and your own notice and plan documents govern your case.