There are two different requests you can make when a prescription costs too much, and almost every article on the subject treats them as one thing. Medicare’s own guidance does not.
A formulary exception asks the plan to cover a drug that is not on its list at all. A tiering exception asks the plan to charge you for a drug it already covers at a cheaper tier than the one it assigned. Same form, same 72-hour clock, very different odds, because in the second case the plan has already agreed the drug is worth covering and you are only arguing about the price.
If your drug is on the formulary but sitting in the specialty tier, you want a tiering exception. Filing for a formulary exception instead is asking a harder question than the one you need answered.
A formulary exception and a tiering exception need different attestations
This is the practical difference, and it is in the standard your prescriber has to meet.
For a tiering exception, per CMS guidance, the prescriber must state that the preferred drug or drugs would be less effective for you, or would cause adverse effects. That is a comparison between your drug and the cheaper alternatives on the lower tier.
For a formulary exception, the prescriber must state that all covered drugs on any tier of the formulary would be less effective or would cause adverse effects, or that step therapy or dose restrictions have failed or are likely to fail or cause harm.
Read those side by side. One asks your doctor to rule out a handful of named alternatives. The other asks your doctor to rule out everything the plan covers. Doctors can and do write both, but the first is a document a busy prescriber can produce in an afternoon and the second is not.
Why this keeps happening
Formularies have been getting narrower, which pushes more people into this process.
Drug Channels Institute reported that for 2026, each of the big three pharmacy benefit managers, CVS Caremark, Express Scripts and Optum Rx, excludes more than 600 products from its formulary. Express Scripts added 129 new exclusions for 2026 against 19 for 2025.
Six hundred excluded products per PBM is the reason the formulary exception exists as a routine consumer process rather than an edge case. A drug you have taken for years can move off the list on January 1 because of a rebate negotiation that has nothing to do with you, and the letter telling you so will not mention that two different remedies exist or that one is easier than the other.
Notice also what the exclusion does to the conversation at the pharmacy counter. The staff can tell you the drug is not covered and what it costs in cash. They generally cannot tell you which of the two exception requests applies to your situation, because that depends on the formulary document rather than the dispensing system.
What a tiering exception is worth
The dollar value depends on the gap between tiers, and here I want to be careful, because I could not find a verifiable current average for specialty tier coinsurance from a named source. Secondary sites quote ranges from 25% to 50% without citing an original survey. Do not trust a specific average, including one presented confidently.
What is documented is the ceiling. For 2026, the Medicare Part D annual out-of-pocket cap is $2,100, up from $2,000 in 2025, under the Inflation Reduction Act’s indexing formula.
That cap changes the shape of the problem in a way worth understanding. On a specialty drug with coinsurance, you hit $2,100 fast and then pay nothing for the rest of the year. On the same drug moved to a preferred brand tier with a flat copay, you may never reach the cap at all, and your total annual cost can land well below it. So the value of a tiering exception is not a percentage saving, it is the difference between spending to the cap every January and spreading a modest copay across twelve months.
For anyone on a commercial plan rather than Medicare, there is no equivalent federal cap, which makes the tier assignment matter more rather than less.
The copay card that may not count
One trap to check before you assume you are covered.
Manufacturer copay assistance cards reduce what you hand over at the pharmacy, but many plans run what is called a copay accumulator, meaning those manufacturer dollars do not count toward your deductible or out-of-pocket maximum. You can burn through $8,000 of assistance and find your own accumulator has barely moved.
If you are relying on a copay card to make a specialty drug affordable, call and ask specifically whether the assistance accrues to your deductible and maximum. If it does not, the card is a cash-flow tool, not progress toward a ceiling, and winning a tiering exception is worth considerably more than it first appears.
Different rules depending on your coverage
Which process you are in determines your deadlines and your escalation path.
Medicare Part D runs a five-level ladder: a coverage determination from the plan, then redetermination by the plan sponsor, then reconsideration by an Independent Review Entity, then an administrative law judge at the Office of Medicare Hearings and Appeals, then the Medicare Appeals Council, then federal district court. CMS requires a decision on a standard exception request within 72 hours and within 24 hours for an expedited request in exigent circumstances.
Marketplace plans run on a different authority than most people assume. Drug exception requests for qualified health plans are governed by 45 CFR 156.122, not the general appeals regulation, and that section carries the same 72-hour standard and 24-hour expedited timelines plus a required independent external review if the plan denies. If your employer self-funds its plan, you generally fall back to the broader internal appeal and external review framework, which does not carry the drug-specific 72-hour mandate.
Step therapy, where the plan makes you fail a cheaper drug first, is increasingly regulated at state level. New Jersey’s law, P.L. 2025 c.50, took effect January 1, 2026 and requires state-regulated plans including its Medicaid and state employee programs to run a transparent override process with 24-hour urgent and 72-hour non-urgent decisions, publish approval and denial statistics, and post clinical review criteria publicly. Counts of how many states have such laws vary between roughly 20 and 29 depending on who is tallying and what qualifies, so ask for the source if someone quotes you a number.
What to do this week
Look up your drug on your plan’s current formulary and write down two things: whether it is listed at all, and if so, which tier. That single check tells you which of the two requests to file.
If it is listed on an expensive tier, ask your prescriber for a tiering exception and make sure the letter addresses the specific preferred alternatives on the cheaper tier by name, explaining why each would be less effective or harmful for you. Generic statements about medical necessity are what denials are made of.
If it is not listed at all, you need a formulary exception, and your prescriber has the harder attestation to write. Ask whether there is a covered alternative worth trying first, because a documented failure on a formulary drug is the strongest support for the exception you will eventually file.
Either way, ask for expedited handling if waiting would harm you, and get the denial reason and the clinical criteria in writing. A formulary exception is a paperwork contest with published deadlines, and the data says most people forfeit it by default. If the plan denies something other than a drug, how to appeal a prior authorization denial covers the same machinery for procedures and imaging.
