Deferred Student Loans

Our AVP of Lending has asked me to consult with this group on deferred student loans and debt ratio calculations.  Specifically, does your credit union exclude or include deferred student loans when calculating debt ratio for loan products.  If you include the deferred loan, how do you calculate the payment . (We currently exclude the debt, but are now rethinking that procedure).  Your feedback is greatly appreciated!  Many thanks! Email is [email protected]