SELECT

-- Member Information
e.Rid, e.LastName, e.FirstName,

-- Invoice Information
--(I need the sum of these two fields in the 2 most recent recrods from this table, chargeable_invoice)
SUM(c.current_premium)
,SUM( c.past_due_amount) 

-- Determine if their Amount Due Exceeds 2X the Premium
(c.past_due_amount-(2*c.current_premium)) As Due

-- Join Member and Invoice Table
FROM 
  employee e 
inner join 
  (select c.accountid,c.current_premium , c.past_due_amount
         ,[Rank] = RANK() OVER (PARTITION BY accountid order by yourDateColumn desc)
   from chargeable_invoice c 
  ) c


on e.account = c.account_id

-- Pull Valid Terminated Members
WHERE e.enrollment is Null and e.Rid is not null 
and c.Rank < 3 


GROUP BY e.Rid, e.LastName, e.FirstName, c.current_premium--, c.past_due_amount