Obtaining Transactions Greater Than 90 Days T-SQL

SELECT ex.ExpenseTypeID, 
       COUNT(*) AS ExpenseType, 
       ext.Description,
       CASE
           WHEN DATEDIFF(day, ExpenseDate, GETDATE()) >= 90
           THEN 90
           WHEN(DATEDIFF(day, ExpenseDate, GETDATE()) >= 60
                AND DATEDIFF(day, ExpenseDate, GETDATE()) < 90)
           THEN 60
           WHEN(DATEDIFF(day, ExpenseDate, GETDATE()) >= 30
                AND DATEDIFF(day, ExpenseDate, GETDATE()) < 60)
           THEN 30
       END
FROM tbl_Expenses ex
     INNER JOIN tbl_ExpenseType ext ON ex.ExpenseTypeID = ext.ExpenseTypeID
WHERE EmployeeID = 88
      AND ExpenseDate <= DATEADD(day, -90, GETDATE())
      AND (Approved = 0
           OR Paid = 0
           AND IsVoided = 0)
GROUP BY ex.ExpenseTypeID, 
         ext.Description,
		 ex.ExpenseDate;