US · guidance
CMS Pub. 100-24, ch. 5, § 5.4
Interest Assessment
CMS assesses interest on past due Medicare premium amounts when the month’s premium
liability is not paid in full by the end of the grace period.
CMS assesses interest in 30-day increments. Interest assessment on Medicare premiums that
remain unpaid by the end of the grace period in which they were due begins with the first day of
the billing month and is calculated on a 30-day basis.
The interest rate for past due Part A and Part B Medicare premiums is the Federal
Supplementary Medical Insurance (SMI) Trust fund rate as computed for new investments in
accordance with section 1841(c) of the Social Security Act (“the Act”). This rate approximates
the actual loss to the SMI trust fund and derives from the average yield on all marketable
obligations to the U.S. Department of the Treasury as of the last day of the month.
History
(Rev. 4, Issued: 08-21-20, Effective: 09-08-20, Implementation: 09-08-20)
Provenance
- Source
- cms.gov
- Retrieved
- 2026-08-25
- Edition
- iom-2026-08-25
- Content hash
8ef4dd85ae770330e5681266e5dca8505307d817b35907ccb64532208906b87d
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