Retirees are bound to be disappointed later this month when Social Security announces the size of the cost-of-living adjustment for 2017 retirement benefits. The nonprofit American Institute for Economic Research estimates that the adjustment will be no more than 0.5 percent, which works out to a monthly income boost of $6 for the average Social Security recipient.

Without any meaningful Social Security payout increase, a smart way for retirees to save money next year is to take the time to shop around for the most cost-effective Medicare prescription drug coverage.

Whether you are enrolled in Original Medicare and purchase separate prescription drug coverage (called a Part D plan) or you are enrolled in a Medicare Advantage plan that includes prescription drug coverage, wringing the most value from your drug coverage can save you plenty more than what even a robust Social Security cost-of-living adjustment might amount to.

“The savings to an individual on the out-of-pocket costs for prescription drugs can be hundreds of dollars or even thousands of dollars by finding the most cost-effective plan,” says Juliette Cubanski, associate director of the nonprofit Kaiser Family Foundation’s Program on Medicare Policy. Yet the foundation reports that less than 15 percent of enrollees make a change to their prescription drug coverage in any given year.

Even if you’ve been happy with your plan in the past, you should still give your coverage a checkup. "Plans are changing a lot from year to year, especially the drug coverage," explains Philip Moeller, author of the recently published "Get What’s Yours for Medicare: Maximize Your Coverage, Minimize Your Costs." “Even if your medications haven’t changed, the cost to you might be a lot higher next year.”

That’s because each year, an insurer’s drug formulary—the medications it covers—can change. That can spell a big hit to your pocketbook. In a survey concerning 20 Part D plans, the Kaiser Family Foundation found that among six of the top drug brands (and one generic drug) the difference between the typical cost when the drug was on a formulary and the highest cost when it wasn’t amounted to at least $200 per month.

The insurer can shift more of the cost to retirees. Insurers usually sort their covered drugs into tiers, ranging from the least expensive and often generic to pricey specialty drugs that require the highest co-pay from the individual.

And there is no uniformity in how similar drugs are priced among plans. A Kaiser Family Foundation study last year found that the monthly out-of-pocket cost for five popular drugs covered by Part D plans can vary by as much as $100.

Rx for Savings

From Oct. 15 to Dec. 7 every year, current enrollees can comparison shop and change their coverage for the next year. Here’s how to make the most of what Moeller calls Medicare’s annual "do over" offer:

Find your plan's Annual Notice of Changes (ANOC). It should have been mailed to you in September. It is the official communication of how your coverage will change.

Focus on changes to drug coverage. Your first step is to confirm that every medication you require is included in your plan’s formulary. Cubanski recommends conferring with your prescribing doctor if a brand-name drug you have been taking is no longer in the formulary or has been moved to a more expensive tier. "Sometimes when a generic becomes available, the brand name will no longer be covered or will be more expensive," she says. "Your doctor may be able to suggest a generic that will meet your needs." If not, you definitely want to shop around for a plan that covers your brand name at a lower cost to you.

Double check your pharmacy. If you’re not using mail order offered by your plan, be sure that your local pharmacy is considered part of your plan’s preferred network; using a pharmacy that isn’t in-network costs more.

Surf your way to savings. The government's free Medicare Plan Finder tool enables you to compare your current plan with other plans available in your area, based on the exact drugs and dosage. (You can compare up to three plans at once.) If you find a better deal tailored to your medical needs, call the plan to confirm what you found online before you make the switch.