If you don't want to create a calendar table, you can do this (which really just creates the calendar table on the fly).

CREATE TABLE #Contracts

(

ContractNumber INT

,ContractStartDate DATETIME

,ContractEndDate DATETIME

,ContractAmount MONEY

);

INSERT INTO #Contracts

VALUES (1234,'01-Jul-2012','30-Nov-2012',5000.00)

,(5678,'01-Jul-2012','30-jun-2013',12000.00)

;WITH StartMonth (sm, nm) AS (

SELECT MIN(ContractStartDate)

,DATEDIFF(month, MIN(DATEADD(month, DATEDIFF(month, 0, ContractStartDate), 0))

,MAX(DATEADD(month, 1, DATEADD(month, DATEDIFF(month, 0, ContractEndDate), 0))-1))

FROM #Contracts),

Tally (n) AS (

SELECT 0 UNION ALL

SELECT TOP (SELECT nm FROM StartMonth) ROW_NUMBER() OVER (ORDER BY (SELECT NULL))

FROM (VALUES ($),($),($),($),($),($),($),($),($),($)) a(n)

CROSS JOIN (VALUES ($),($),($),($),($),($),($),($),($),($)) b (n)),

MyContracts AS (

SELECT ContractNumber

,ContractMonth

,ContractAmount=CASE WHEN ContractStartDate > ContractMonth OR

ContractEndDate < ContractMonth THEN 0

ELSE ContractAmount/(DATEDIFF(month, ContractStartDate, ContractEndDate)+1) END

FROM #Contracts a

CROSS APPLY Tally b

CROSS APPLY (SELECT ContractMonth=DATEADD(month, n, ContractStartDate)) c)

SELECT ContractNumber

,[Jul]=MAX(CASE WHEN MONTH(ContractMonth) = 7 THEN ContractAmount END)

,[Aug]=MAX(CASE WHEN MONTH(ContractMonth) = 8 THEN ContractAmount END)

,[Sep]=MAX(CASE WHEN MONTH(ContractMonth) = 9 THEN ContractAmount END)

,[Oct]=MAX(CASE WHEN MONTH(ContractMonth) = 10 THEN ContractAmount END)

,[Nov]=MAX(CASE WHEN MONTH(ContractMonth) = 11 THEN ContractAmount END)

,[Dec]=MAX(CASE WHEN MONTH(ContractMonth) = 12 THEN ContractAmount END)

,[Jan]=MAX(CASE WHEN MONTH(ContractMonth) = 1 THEN ContractAmount END)

,[Feb]=MAX(CASE WHEN MONTH(ContractMonth) = 2 THEN ContractAmount END)

,[Mar]=MAX(CASE WHEN MONTH(ContractMonth) = 3 THEN ContractAmount END)

,[Apr]=MAX(CASE WHEN MONTH(ContractMonth) = 4 THEN ContractAmount END)

,[May]=MAX(CASE WHEN MONTH(ContractMonth) = 5 THEN ContractAmount END)

,[Jun]=MAX(CASE WHEN MONTH(ContractMonth) = 6 THEN ContractAmount END)

FROM MyContracts

GROUP BY ContractNumber

DROP TABLE #Contracts

If you have an unknown number of months, you'd need to convert this to Dynamic SQL, making the column headers something like [mmm-yy] and modifying the MONTH = test within the CASE accordingly.

You might note how I have normalized the contract start dates to the first of the month and the contract end dates to the end of the month.