You already know about nested IF statements- you might add an IF to
your existing formula that says IF(one frequency, 3 incomes,"See
Guideline Chart",IF(D10<=(A10*'Income Eligibility
Guidelines'!D2+'Income Eligibility
Guidelines'!D1),"Free",IF(D10<=(A10*'Income Eligibility
Guidelines'!E2+'Income Eligibility Guidelines'!E1), "Reduced","Paid")))