Results of Sql to a Variable

I have a financial query that uses Sum() multiple times in different calculations. The query is very slow because the sum() function has to rerun multiple times in the query. Is there a way to store the results in a variable and reference the variable later in the query rather that redoing the sum() again? Query follows:

/************************************************************************************
Name:             Case Type Balance Report
Date Created:     1/12/2011
Created By:       Mike Gee 
Purpose:          To report financial info for each case type. 
Modifications:    mm/dd/yyyy - [Name] - [Description]

************************************************************************************/
DECLARE @NetAmt money;  --I would like to load results to a variable like this...

SELECT      fc.CASE_NUMBER 
 ,fc.CASE_CATEGORY_TYP_CD
 ,AFM_V_COST_DETAILS.COST_TYP_DESC

 ,(Select IsNull(SUM(CREDIT),0) 
          From afm_v_cost_details cd2
          where ID = 'RV' 
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) as 'TOTAL VOIDS (CODE=RV)'


 ,(Select IsNull(SUM(DEBIT),0) 
          From afm_v_cost_details cd2
          where ID = 'RP' 
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) as 'AMOUNT PAID (CODE=RP)'


 ,(Select IsNull(SUM(CREDIT),0) 
          From afm_v_cost_details cd2
          where ID = 'RV' 
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) -
          (Select IsNull(SUM(DEBIT),0) * -1
          From afm_v_cost_details cd2
          where ID = 'RP' 
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) as 'NET AMOUNT'


,(Select IsNull(SUM(CREDIT),0) --assessments 
          From afm_v_cost_details cd2
          where ID = 'RC' 
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) as 'RECEIVABLE ASSESSMENTS (CODE=RC)'



,(Select IsNull(SUM(DEBIT),0) --RECEIVABLE VOIDS/ADJUSTMENTS
          From afm_v_cost_details cd2
          where ID in('CV','CA') 
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) as 'TOTAL RECEIVABLE VOIDS/ADJUSTMENTS (CODES=CV,CA)'


,(Select IsNull(SUM(CREDIT),0) 
          From afm_v_cost_details cd2
          where ID = 'RC' 
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) -
          (Select IsNull(SUM(DEBIT),0) * -1
          From afm_v_cost_details cd2
          where ID in('CV','CA')
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) as 'NET ASSESSMENTS (CODE RC - CV,CA)'



,(Select IsNull(SUM(CREDIT),0) 
          From afm_v_cost_details cd2
          where ID = 'RC' 
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) -
          (Select IsNull(SUM(DEBIT),0) * -1
          From afm_v_cost_details cd2
          where ID in('CV','CA')
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) +
          (Select IsNull(SUM(CREDIT),0) 
          From afm_v_cost_details cd2
          where ID = 'RV' 
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) -
          (Select IsNull(SUM(DEBIT),0) * -1
          From afm_v_cost_details cd2
          where ID = 'RP' 
          AND  (cd2.COST_TYP_DESC = 'PROBATION') 
          and cd2.case_number = fc.case_number ) as 'BALANCE = (NET ASSESSMENTS - NET AMOUNT)'



FROM         dbo.AFM_V_COST_DETAILS INNER JOIN
             dbo.ACM_FACTS_CASE fc 
             ON dbo.AFM_V_COST_DETAILS.CASE_ID = fc.CASE_ID


WHERE     (dbo.AFM_V_COST_DETAILS.COST_TYP_DESC IN(@CostTypeCd)) -- use "PROBATION" for JV 
         AND (fc.CASE_CATEGORY_TYP_CD IN(@CaseType)) 



GROUP BY fc.CASE_NUMBER,fc.CASE_CATEGORY_TYP_CD,AFM_V_COST_DETAILS.COST_TYP_DESC

ORDER BY fc.CASE_CATEGORY_TYP_CD, AFM_V_COST_DETAILS.COST_TYP_DESC, fc.CASE_NUMBER