Our place is funny (massive international bank).
Official guideline is “Business casual” (which translates to no tie or jacket required) in the office & suit if meeting clients / external.
A couple of levels above me, people all wear suit & tie, even though they rarely have an external meeting or meet clients.
A couple of levels above that, it starts going more casual. The CIO wears whatever the hell he wants – usually flip flops and shorts, but he does work in California.
I can relate to that, when I was in banking it was the big bosses to dropped the ties first, well at least when they wern’t been hauled in front of a select committee or something.