Modification of factoring rule based on customer requirment

Dear All,

Our customer requirement is such that factoring should not be done based on the no of actual calendar days ,it should be always

30 irrespective of the no of day in the month.

Factoring should be always be 30 irrespective whether month is jan or feb or nov.

Kindly let me know how to address the problem

Regards,

Prince Elvis