Where every figure comes from
Each number on this site traces to a document below. We cite CMS, SSA and the statute directly — never another blog, broker or comparison site, however convenient.
Annual figures
| Year | Document | Published | Provides |
|---|---|---|---|
| 2026 | CMS Medicare Parts A & B premiums and deductibles | 2025-11-14 | Standard premium, MAGI brackets, Part B and Part D IRMAA |
| 2025 | CMS Medicare Parts A & B premiums and deductibles | 2024-11-08 | Standard premium, MAGI brackets, Part B and Part D IRMAA |
| 2027 | CMS Part D national average bid | 2026-07-28 | Part D base premium only. No MAGI brackets or Part B figures published yet. |
Standing references
| Document | Provides |
|---|---|
| SSA POMS HI 01101.020 | The IRMAA sliding-scale tables and their interval rules |
| SSA POMS HI 01101.031 | How IRMAA is calculated; the 25/35/50/65/80/85% cost shares |
| Social Security Act §1839(i)(5), 42 U.S.C. §1395r(i)(5) | How the MAGI thresholds are indexed each year |
What we do not cite
Insurance brokers, comparison sites and general-interest finance media all publish IRMAA tables, and most are copied from the documents above. Copying a copy is how errors spread and outlive their correction — so we go to the source, and tell you which one.
If a figure here disagrees with CMS or SSA, the source wins and we are wrong. See our method for how each number is handled.