margin maintenance requirements for short SPX options

SPX today is around 6500 and I've observed (using IBKR portfolio margin) the amount I need equity to short one SPX option thats well out of the money is around 10% of the total SPX value of one contract or about 65K.

So if I have 65K in equity, I can approximately short one OTM SPX option and be able to maintain that position.

Curious from everyone's experience, how does that 65K maintenance requirement change if:

1. theres a big spike in VIX but the option continues to remain well OTM.
2. SPX has a big move and the option is now right at the money, is the maintenance requirement still about 10% or 65k?
3. if the option is now in the money? Is it the 10% or 65K + the amount thats in the money? So if its 5% in the money, then you need almost 15% or 100K to maintain the position