The federal government recently redesigned a digital tool that helps seniors navigate complicated Medicare choices, but consumer advocates say it’s malfunctioning with alarming frequency, offering inaccurate cost estimates and creating chaos in some states during the open enrollment period.

More than 60 million people use Medicare, which covers those over 65 and the disabled. Users have to pick their plans annually. The current open enrollment period ends Dec. 7. Medicare advisers — as well as advocates for seniors — worry that the full weight of the tool’s inaccuracies will not be felt until the 2020 coverage year begins and seniors head to pharmacies to fill prescriptions or show up for medical appointments. For many Medicare participants, selections made during open enrollment are irreversible.

As open enrollment goes into the home stretch Thanksgiving week, critics say the new plan finder tool can create confusion by obscuring out-of-pocket costs that seniors should factor into their decisions…

“If they pick the plan based solely on the premium they are likely getting a plan that could cost them thousands more in a calendar year,” said Christina Reeg of the Ohio Department of Insurance. She heads a program that helps Medicare enrollees try to find the right plan.

If you’re going to make Medicare coverage changes that include dropping or buying a supplemental plan — aka, Medigap — make sure you know the rules that come along with it.

Connecture’s SVP of Federal Programs Jim Yocum spoke with Money Magazine to discuss some of the potential implications from the White House’s recent efforts to curb drug costs. Connecture data was used in the analysis.