I live in NY. My divorce agreement clearly indicates that my ex's salary will never be considered lower than $50,000. He was paying me $961.68/month. He recently reduced that amount to $200/month. How far in arrears does he have to be before I can pursue collecting the balance in family court?

If he didn't clear it with the courts then he goes into arreas right away. If he is paying through and agency then you need to make sure you let them know. Otherwise you may have to go back to court and get it that way. Is this through wage assignment ?

One month, but he can of course go back to get the original order modified. If he loses his job for example or gets one paying 20,000 the court will considered changing the order.

But he can not change the amount to be paid without a court order