Changes are ahead next year for Medicare, and important deadlines are quickly approaching.

Whether you have been in Medicare for quite a while or are new to the federal health plan for individuals over 65, there are some important changes to the program for 2018.

Medicare experts strongly suggest that even if you are satisfied with your current coverage you should review your plans during open enrollment, which closes Dec. 7.

Here’s what’s new for 2018:

Part B premiums: Medicare Part B pays for doctor visits and other outpatient services.

• If you are on Medicare but not yet collecting Social Security benefits, your Part B monthly premium is expected to hold steady at $134.
• If you are collecting Social Security, which automatically pays your Part B premium, you’re paying about $109 a month in 2017 because of a law that prevents Medicare premiums from lowering Social Security payments. That amount could change for 2018 depending on how the 2 percent Social Security cost-of-living adjustment (COLA) affects your individual monthly payment.

Medicare Advantage (MA) premiums dip: The average monthly premium is expected to be about $30 next year, a slight decrease of $1.91 a month. MA plans are a private insurance alternative to original Medicare. They cover Part A (hospital), Part B (doctor and other outpatient services) and usually Part D, prescription drugs. Note: This is just an average. Premiums vary widely based on where you live and what your plan covers.

More choice of MA plans: The number of MA plans available across the country is increasing. In 2018, 99 percent of Medicare beneficiaries will have access to an MA plan, and 85 percent will be able to choose among 10 or more MA plans.

Prescription drug (Part D) premiums dip: These monthly charges are expected to decline slightly to an average of $33.50, compared with $34.70 a month in 2017. This premium decline will be the first for Part D since 2012. Premiums vary by where you live and what plan you select. Make sure your current plan still covers all your medications — and explore the cost.

Part D coverage gap narrows: Once the total cost of your prescriptions reaches a certain threshold — set each year by the federal government — you pay more for your prescriptions. That’s because of a quirky aspect of Part D called the coverage gap, also known as the doughnut hole. For 2018, once you have incurred $3,750 worth of drug costs, you’ll be in the coverage gap. At that point, you’ll pay 35 percent of the cost of brand-name drugs and 44 percent of generics. You’ll continue to pay those prices until the total cost of your drugs reaches $5,000. Once you’ve hit that limit, you’ll no longer be in the doughnut hole and you’ll pay no more than 5 percent of your drug costs for the rest of the year.

The doughnut hole has been narrowing each year since the Affordable Care Act was passed in 2010. The gap will close in 2020, and beneficiaries will pay 25 percent of the cost of all their prescriptions.

High-income surcharges: Medicare beneficiaries with incomes at a certain level pay higher Part B and D premiums. What’s different for 2018 is that more people will be subject to these surcharges because the income thresholds have changed. For 2018, if you are an individual earning $133,500 a year or a couple earning $267,000 a year, your premiums will increase. You can find the complete chart of the surcharges at Medicare.gov.