One of the biggest changes takes effect in 2025. Part D drug plans must cap out-of-pocket spending on covered drugs at $2,000 a year. It will benefit enrollees with high drug costs by allowing enrollees to pay their prescription costs monthly rather than all at once.

Medicare's 2025 enrollment began Tuesday and runs through Dec. 7. Seniors should verify their Medicare plan and prescription drug changes.

Here are five Medicare Part D changes coming next year and what you need to know about them to be an informed shopper during open enrollment, which begins today and ends Dec. 7.