"Extra forms" for Part B late enrollment are required regardless of when/if you signed up for Part A doesn't affect the Part B forms. You still need them completed if you had EGH since T65 and you want to avoid the penalty.
I have a number of folks who enroll in B past 65. They can sign up online, or in person. The link provided gives you a "how to" step by step.
I already told him about the employer form and I also had many sign up for Part B late
this was the first part A after 65
they told him he should never have had signed up for part A online or separate from the part B as this caused additional forms to undo what was done
at that point he only applied part A, online, he said he did not get a confirmation email so he called and this is what they told him
and that I was misinformed about signing up for Part separately from the B and singing up for Part A online when older then 65
whatever I never ran into anyone older then 65 needing part A before, and hope I never do again
the whole thing was wierd