@e994792f
Based on what indications you have given on his income, it sounds like you are right - His Medicare Part A won't be completely free due to his lack of working under the system for long enough to get it "free". He will have to do a buy-in - but that might not be as big a deal as you think. The price of a Medicare Part A buy-in will be proportionate to the amount of time that he did work and pay Medicare taxes - if he can get those credits up to at least 30, there is a substantial difference in the price (see the link below). These cost are what are now in effect in 2021 - by the time he gets to 65 years old, if nothing has changed with the program, the cost for all the Parts of Medicare will probably be higher.
Medicare.gov - 2021 Cost at a Glance
from the link ~
Most people don't pay a monthly premium for Part A (sometimes called "premium-free Part A"). If you buy Part A, you'll pay up to $471 each month in 2021. If you paid Medicare taxes for less than 30 quarters, the standard Part A premium is $471. If you paid Medicare taxes for 30-39 quarters, the standard Part A premium is $259.
Everybody on Medicare, unless they are deemed to be very low-income eligible, also pays a Part B premium each month. For most people on Medicare in 2021, this monthly cost is a $148.50 per month with higher income seniors paying more.
You can read about Part B premiums and also Part D premiums at the above link also.
Nobody knows what his cost will be by the time he reaches 65 but this will give you an idea of the 2021 cost. Anything can happen with medical cost - there are no assurances.
It's Always Something . . . . Roseanna Roseannadanna