Spot,
Humana will show up first because Part D is run by CMS (Medicare). The Mutual of Omaha plan should show up in a couple weeks under the "other insurance" tab.
As far as the ACA, what they told you was correct. If someone else (spouse) is staying on the ACA plan, you want to call the day before your coverage starts.
https://www.healthcare.gov/reporting-changes/cancel-plan/ - here is a link.
IMPORTANT - If you are cancelling the entire plan, make sure you give them at least 14 days to cancel. This year they have finally made it possible to cancel in advance. Last year it was cancel the day after you called in. There
was no way to cancel on a future date last year...unless that date was the next day. Now you have to give them a 14 day notice at least.
You want to make sure that's handle because it could cause some issues the following year when you do your tax return. Here is an example: You pay $25 a month, the government subsidy is $475. You go on to Medicare in June, but you forget to cancel your plan until August. The ACA law says Medicare is "creditable coverage" and you cannot have both at the same time. So you could possible owe the $475+$25 back to the government for each month you had both Medicare and ACA. Even though the $475 went to the insurance company, it went on your behalf.
You can call Healthcare.gov at 800-318-2596 at any time (24/7). Our experience is that the late shift tends to have more knowledgeable people on it...for whatever reason.
Here is another strange glitch with the ACA. You will find that when you cancel yourself off ACA and leave your spouse, your premium might change slightly. Remember that both of you are getting a subsidy, so when one drops coverage for Medicare, the subsidy will drop also. Remember, even if they are on Medicare, you still have to count them as part of your household (household is how many people on your tax return).
Here are a couple other issues to be aware of:
What income counts:
https://www.healthcare.gov/income-and-household-information/income/
More on Medicare:
https://www.healthcare.gov/medicare/changing-from-marketplace-to-medicare/
Hope that helps! Welcome to Medicare..."come on in the water's fine" ("Oh Brother where art thou" reference)
Thanks
Rusty Williams