Medicare open enrollment runs from Oct. 15 to Dec. 7. During this period, seniors 65 and older, and other Medicare enrollees, can switch providers of their comprehensive health and drug plans. Here's a guide to some of the choices they face.

BASIC MEDICARE

More than 830,000 Oregonians are enrolled in some form of Medicare insurance, according to U.S. Centers for Medicare & Medicaid Services data. About 453,000 of them stick with basic coverage, known as Parts A and B.

Premiums: $135.50 is standard in 2019, up from $134 in 2018, according to the U.S. Centers for Medicare & Medicaid Services. Higher-income taxpayers (singles making more than $85,000 a year or couples earning more than $170,000) will pay considerably more — likely in the $188 to $455 a month range, and about 3.5 percent of enrollees will pay less than the standard rate.

Enrollment periods: There's a seven-month enrollment window starting three months before the month you turn 65. Those who miss this initial enrollment period can sign up between Jan. 1 and March 31 each year. Those who are 65 and older and still working have eight months after their employment ends or group insurance coverage terminates to enroll.

MEDICARE ADVANTAGE

About 376,000 Oregon Medicare enrollees, or 45 percent, choose to pay a bit extra for private insurers to deliver their medical coverage, federal data show. That's one of the highest U.S. enrollment rates, and it's significantly higher than the 34 percent reported nationwide. Most of those plans also offer prescription drug insurance known as Part D. Multnomah County has one of the highest Medicare Advantage penetration rates of any county, at 59 percent, according to government data.

Premiums: $0 to $201 per month in 2019 among plans in the Portland market.

Enrollment period: Oct. 15 to Dec. 7

PRESCRIPTION DRUG PLANS

Another 262,000 enrollees in the state buy stand-alone prescription drug plans, federal data show. These Part D plans cover medications only, not care.

Premiums: $14.50 to $117 a month in 2019, according to The Oregonian/OregonLive's analysis of federal data. The government projects the average premium will decline for the second consecutive year, by $1.09 to $32.50 a month. But actual changes vary widely across all 19 plans, from a 55 percent decline to a 30 percent increase, the analysis shows. High-income enrollees also pay a surcharge for Part D coverage, which in 2019 will range from $12.40 to $77.40 per month.

Enrollment period: Oct. 15 to Dec. 7

MEDIGAP

About 155,000 residents choose supplemental Medicare coverage, known as Medigap, according to the Oregon Division of Financial Regulation. These policies cover deductibles for Parts A and B, copays and other cost-sharing requirements that basic Medicare doesn't.

Premiums: $30 to $457 per month in 2019, depending on age and plan type, according to state data.

Enrollment period: Only for six months beginning with the month of your 65th birthday or when you otherwise become eligible. After that, seniors can still buy a policy, but an insurer can, with some exceptions, deny coverage or price it based on an existing health condition.

Birthday rule: In Oregon, seniors can switch Medigap plans during a 30-day period that starts with their birthday. This rule allows them to move to the same type of plan offered by a different insurer or to a different type of plan with fewer benefits. Seniors in employer-sponsored group Medigap plans are not eligible for this rule.

Brent Hunsberger is an investment adviser representative in Portland. For important disclosures and information about Brent, visit bit.ly/2dwmN7w. Reach him at OregonianMedicare@gmail.com or leave a message at 503-683-3098.