Account.Class_of_Trade__c = Residential
Account.Terms__c = Net 30 Days

IF(
    OR(
        AND(ISNEW(), [Account].Run_Credit_Report__c),
        AND(
            ([Account].Run_Credit_Report__c),
            ISCHANGED([Account].Run_Credit_Report__c)
        )
    ),
    true,
    false
)