e-legal lesson

The term due in this sense (mind you, not in others such as due care, due diligence, due consideration) means owing; payable; justly owed. That which one contracts to pay or perform to another; that which law or justice requires to be paid or done. Owed, or owing, as distinguished from payable. A debt is often said to be due from a person where he or she is the party owing it, or primarily bound to pay, whether the time for payment has or has not arrived. The same thing is true of the phrase due and owing.

The phrase due or to become due is standard in contract drafting, but it’s also awkwardly archaic. You can easily make it clearer:

. . . any payments due or to become due

[read that are then due or that become due] in respect of that Collateral . . .