I copied your code to an SQL re-formatter. It did not give an error???
Code:
SELECT t01Month.MntID038
,IIf([MntID038] = 1, [FirstMnthInPerfac038], DateAdd("m", [AmtMnths038], [FirstMnthinPerfac038])) AS FstDayOfMnth038
,DateAdd("m", 1, [FstDayOfMnth038]) - 1 AS LstDayOfMnth038
,MonthName(Month([FstDayOfMnth038])) AS MonthName038
,Year([LstDayOfYear038]) AS Year038
,DateSerial(IIf(Month(DLookUp("FirstMonthPerfac020", "q01BusinessInformation")) > Month([FstDayOfMnth038]), Year([FstDayOfMnth038]) - 1, Year([FstDayOfMnth038])), Month(DLookUp("FirstMonthPerfac020", "q01BusinessInformation")), 1) AS FstDayFinYer038
,DateAdd("yyyy", 1, [FstDayFinYer038]) - 1 AS LstDayOfYear038
,t01Month.Workingdays038
,- INT (- IIf([LstDayOfYear038] - DLookUp("StartDate020", "q01BusinessInformation") < 0, 0, [LstDayOfYear038] - DLookUp("StartDate020", "q01BusinessInformation")) / 365.25) AS YearNumforBus038
,DateSerial(Year([FstDayOfMnth038]), Month([FstDayOfMnth038]), 1) AS FstDayOfMnth038b
,[MntID038] - 1 AS AmtMnths038
,DLookUp("FirstMonthPerfac020", "q01BusinessInformation") AS FirstMnthInPerfac038
,DLookUp("StartDate020", "q01BusinessInformation") AS FstMnthInBusiness038
,IIf((Year([FstDayOfMnth038]) - Year([FstMnthInBusiness038])) * 12 + Month([FstDayOfMnth038]) - Month([FstMnthInBusiness038]) < 0, 0, (Year([FstDayOfMnth038]) - Year([FstMnthInBusiness038])) * 12 + Month([FstDayOfMnth038]) - Month([FstMnthInBusiness038]) + 1) AS MonthNumInBus038
FROM t01Month;