#1 Rule - CALL them and ensure they really do want to be paid via ACH.  We have recently had two separate incidents where we got emails from the sub asking for ACH payment and upon calling to confirm discovered their email had been hacked. Had we accepted what was sent via email we would be out a bunch of money. Do the due diligence to ensure the money is going to the right place!

Siri: Thanks for the advice!  Never would have imagined that happening.  Kim:  I would call the bank.  I think you only can put one bank account per amount on a ACH.  It sounds like the subcontractor doesn't want to pay the suppliers.  In our state, that could leave you exposed to some liability to the suppliers.