For aging adults living on fixed incomes, every penny counts. But the majority of elders on Medicare appear to be leaving hundreds of dollars on the table, according to a new analysis.

Little more than five percent of seniors succeed in selecting the ideal Medicare prescription drug benefit plan (Part D), say researchers from the University of Pittsburgh, Graduate School of Public Health.

The typical beneficiary is losing somewhere in the ballpark of $368 per year because they're failing to choose a plan that covers their needs, but doesn't require them to pay unnecessary premiums.

The older they are, the more likely an elder is to overspend. People in their late 60s paid an average of $30 less in pointless payments per year than those in their 80s.

Researchers point out that the results of their study mimic trends seen in previous years.

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"When Medicare Part D is started, the majority of beneficiaries do not choose the least expensive plan," says Chao Zhou, Ph.D., lead author of the study in a press release. "Over time, seniors simply stick to their original plan and never switch to a better one. Beneficiaries might not spend much time researching and adjusting their plan choices based on changes in their medication needs and plan options."

Seniors who find themselves in sub-optimal plans have the opportunity to save money during the annual Medicare Open Enrollment period.

For more information on how to optimize your savings during open enrollment, visit the Medicare Open Enrollment Guide .