I went into Medicare enrollment thinking I understood it. I did not.
The 7-month enrollment window around your 65th birthday — I knew about that. What I did not know: if you delay Part B because you're still on employer coverage, the clock starts when your employer coverage ends, not when you turn 65. I nearly missed my Special Enrollment Period because my HR department gave me wrong information.
Also: Medigap vs Medicare Advantage is a much bigger decision than it looks on the surface. Medigap costs more monthly but the predictability is worth it if you travel or see specialists. Medicare Advantage has lower premiums but the network restrictions can bite you hard.
What did you learn the hard way? What do you wish someone had told you before you hit 65?