@xStork
As a Medicare beneficiary, every year a booklet called "Medicare and You" is issued to you either in booklet form or online. Medicare and You 2021 Handbook Everything you have asked about is discussed in the handbook - Section 6 is devoted to Medicare drug coverage (Part D).
Much of this is also covered in the plan details that your current insurer sends you.
Once your Initial Enrollment period ( when you 1st qualify for Medicare) is over, plans are generally written and issued for a calendar year January 01 - December 31. The plan that you opt for during Open Enrollment (October 15 - December 7) each year, whether new or sticking with the current one, are for the policy period of January 01 - December 31.
EVERY year during Open Enrollment period beneficiaries can SHOP and change, if they want, their Medicare Part D coverage. Things change from year to year either on the beneficiary side OR the insurer side. A beneficiary should always re-evaluate their current plan compared to other new plans offered in their area during this OPEN ENROLLMENT period. Remember the insurers also change their plans too - what's covered in their formulary, what tiers are assigned to which meds, what pharmacies are covered - from mail order to community, any special qualifications for any meds, the new deductible, co-pays and premiums and more. Again this open enrollment period is from October 15 - December 7 EVERY YEAR.
Outside of these enrollment periods, there is only a SPECIAL ENROLLMENT period - you have to be eligible, meeting certain defined criteria, for this mid-cycle change in plans..
The late enrollment penalty that you picked up from being late to the party initially - last forever - it is based on a specific % times the number of months that you were late signing up - and yes, these number of months can be added to if you go over that # of day limit - adding more to the (forever) penalty.
You are making lots of mistakes - costly ones - I urge you to get that Medicare and You 2021 Handbook - read it and if you still don't understand it - ALL of it, ALL of Medicare too, then get some local help.
Help can be found in your area or state by contacting an independent MEDICARE insurance broker that writes for many different companies that services your area OR perhaps from your state - SHIP (State Health Insurance Program) volunteers. Medicare.GOV - Contact Info locator
Medicare and all its various parts is a complicated program but just like any other insurance plan, you need to understand it or have somebody to help you work through it. Medicare is a government program with millions of people on it and thus the government make pretty strict and explicit rules that we all have to follow -
Some additional links for you from Medicare.GOV
MEDICARE.GOV - How to drop your Medicare drug plan
MEDICARE.GOV - Part D late enrollment penalty
MEDICARE.GOV - 3 ways to avoid the Part D late enrollment penalty
More links to Medicare Part D info on the left side of the page
ALL of this is covered in the Medicare and You 2021 Handbook.
Your Questions:
My question is, am I still obligated to pay the last two months of the old plan I had cancelled? Despite my cancellation, does the plan remain in effect till the next plan takes over?
Sounds like to me that you finished paying for the 12-months of coverage under the Humana Walmart plan with your additional payments to them. But you may owe them (2) more cause you gave no dates of coverage or premium months.
Make sure Medicare knows that you have switched plans per instructions as how to advise them.
Same thing on what premium periods you paid on the new plan - the SilverScripts plan through Aetna. Read your Plan - what's the period of insurance, most likely 01/01 - 12/31
Figure it up by premium period for both.
It's Always Something . . . . Roseanna Roseannadanna