Do you need to sign up every year for Medicare and co-insurance?

Thanks!
Their supplemental or secondary insurance is Cigna. There's no sign of them paying a premium to Cigna in their bank account.
I'll reach out to our Aging agency her in Austin and see if they can help navigate further. I appreciate all your advice.

Like said, Medicare is a one time thing. No renewal. This is open enrollment for supplimentals. You may notice a lot of mail from different Insurance co. wanting u to pick them. If ur happy with what u have no change is made but if you want to change this is the time to do it. Check ur parents bank ststements. Supplimentals like to do automatic withdrawl. If this is what is happening then ur OK. Premiums are being paid.

The insurances needed for the 20percent Medicare doesn't pay are called supplimentals. They are many kinds depending on the persons need and how much out of pocket they can afford to pay. There are Medigaps, as mentioned and Medicare advantages. One provides perscriptions and one doesn't. First thing u could d was call their primary doctor and see what insurance they have on file. Their pharmacy should have the prescription plan they use. They may have opted to take Medicare part D which gets deducted from their SS check. You can call your local office of aging. They may hae someone who can help you if you find they defaulted on their insurance payment. You might want to check and see if the company/s they retired from supply their medical supplimental. This is a tricky process so you will need help sorting it out. Good Luck.

Once they've signed up, they don't need to register again. Typically premiums are deducted directly from SS, at least that's my experience.

If by co-insurance you mean gap insurance, the only plan of which I can speak is the BCBSM Medigap Plan C. Premiums are billed and paid monthly. If they're not, coverage can lapse.