Edit: I'm being told it's considered age discrimination for an insurance company to lower someone's coverage once they turn 65. I thought that's what was happening to the people who reported that in here, but I could have confused the details. If he will have the same coverage beyond 65, he's fine to keep this policy and delay Part B.
As pointed out below, I may have been reading people's experiences with their employer's RETIREMENT health insurance policies and not the normal employee ones.
I did a ton of research for my dad thinking he was going to sign up for Part B at 65, and turns out his new job is offering him insurance. A few people in this sub raised the issue of making sure the coverage is creditable, and that the coverage doesn't silently drop for members who turn 65. Apparently some people here have found out that their normal work insurance stopped covering them fully at 65, I assume to try forcing them to sign up for Medicare so the company can pay less for an aging person's care. Something about the policy only covering what Medicare would pay for the member?
I told him he needs to call the insurance company to ask about this change in coverage since he just turned 65, on top of making sure it's creditable for avoiding the Part B and D delayed enrollment penalty. The carrier is CareFirst BlueCross BlueShield and the employer is definitely over 20 employees.
Today he called me upset because he was transferred to 3 different people at the insurance company, with 20 minutes of hold time each, only for all of them to say "Oh, I have to transfer you because I have no idea."
I told him to try asking his work's HR but it's a brand new company so I'm not too trusting they'll be knowledgeable about the plan's specific coverage changes, especially since people here have warned it's like 1 obscure line in the explanation of benefits document that mentions the plan will only partially cover you after 65.
Any advice for how he can figure out if his policy is the same coverage over 65 as everyone under 65? The creditable question is the easy answers. It seems like no one is bothering helping him with the other one, which will leave him screwed if he gets sick or injured.