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XIFAXAN is a brand of rifaximin. What agents check before quoting it: how many 2026 Part D plans cover it, on which tier, with what restrictions and copays, by plan type, carrier and state.
In 2026, 5,496 of 5,496 Medicare Part D and Medicare Advantage drug plans (100%) list XIFAXAN on their formulary, across 328 of 328 formularies. The most common placement is tier 4 (2,680 plans, 48.8% of those covering it). 5,188 of the covering plans require prior authorization (94.4%), 0 step therapy and 2,933 a quantity limit.
508 covering plans charge a flat copay for a 30-day supply at a preferred retail pharmacy after the deductible — median $47, 81 of them $0; 4,988 charge coinsurance instead — median 27% of the drug's cost. Once a member's out-of-pocket drug spending reaches $2,100 in 2026, covered drugs cost $0 for the rest of the year.
XIFAXAN has a Medicare negotiated price (maximum fair price) of $1,000 for a 30-day supply, which takes effect in 2027. The negotiated price lowers what the plan pays; the member's copay or coinsurance still follows the plan's tier.
2025: 5,631 of 5,631 plans covered it (100%); 2026: 5,496 of 5,496 (100%).
Of 4,368 plans offered in both years, 0 added it to the formulary and 0 dropped it.
Among plans covering it both years, 140 moved it to a higher tier and 22 to a lower one; 4 added prior authorization and 0 removed it.
Medicare Part D paid for 429,294 30-day fills of XIFAXAN in 2024 for about 104,760 enrollees, at an average total cost of $2,652.13 per 30-day fill (CMS Part D Prescribers by Geography and Drug, national).
Price XIFAXAN and the rest of a client's list on every plan in their county.
Estimate XIFAXAN costs by plan
Free tools for licensed insurance agents. Data from CMS public files; verify with plan documents before advising a client.
Counts are over every Medicare Advantage drug plan and stand-alone Part D plan in the CMS monthly formulary files, excluding employer plans. A plan counts as covering a drug when any strength or form of it is on the plan’s formulary; the tier, prior authorization, step therapy and quantity limit shown are the most favorable version on that formulary. Copays are for a 30-day supply at a preferred retail pharmacy after the deductible. This is a reference for licensed agents, not a plan recommendation; verify with the plan’s formulary before advising a client. Source: CMS Part D formulary files (release 09/16/2026). CMS formulary data.