The standard monthly Part B premium for 2025 is $185.00, which is what most people will pay. However, if your modified adjusted gross income, as reported on your IRS tax return from 2 years ago is above a certain amount, you’ll pay the standard premium amount, and an Income Related Monthly Adjustment Amount (IRMAA).
2025 IRMAA for Part B and Part D based on 2023 income (2-years prior)
Source: https://www.cms.gov/
Source: https://www.cms.gov/