You and your in-laws can review the options of switching to a medigap/Medicare supplement and stand-alone drug plan or to a Medicare Advantage HMO plan. Will their medical and drug costs be lower, the same or higher? What plans most effectively cover their medical and drug needs. If they are looking at a Medicare Advantage plan, are all of their current physicians in the same medical group and do they accept any Medicare Advantage plans? Please be aware that if they leave the employer retiree plan, they will not be able to get back on it.
Should they decide to leave the employer plan, they would have a special election to sign up for their Medicare insurance choices providing they have requested termination from the employer plan and have a letter confirming that termination.
Also be aware, that many couples do not carry the same insurance. If one of the spouses needs freedom of choice regarding providers, then that spouse may elect the medigap policy and stand-alone drug plan whereas a Medicare Advantage HMO will work well for the other spouse.
Do not rush into making this decision. Take time to evaluate and compare options before making any decision.