I need to create a query with columns containing quarterly figures. I figured I could handle that with subqueries, but I am trying to make this work for a long time already and it still does not seem right.
The final result now gives the correct figures, but I cannot add the last quarter to it because of the join with the GL accounts, if there is no result in the subquery, it drops the entire line.
I must be doing something wrong, but I can't figure out how to correct it.

I hardcoded the where clauses and removed some fields to make it more readable:

SELECT  Departments.deName,
		GLSub.gsAccount AS Account,
		Total.itAmount AS Total,
		JanMrt.itAmount AS JanMrt,
		AprJun.itAmount AS AprJun,
		JulSep.itAmount AS JulSep,
		JanMrt.itAmount + AprJun.itAmount + JulSep.itAmount AS Test
	FROM PayEmps
	
	JOIN Departments
		ON Departments.DeKey = PayEmps.paDeKey
		
	JOIN Runs
	ON Runs.ruKey = PayEmps.paRuKey

	LEFT JOIN 
	(SELECT IT.itGsKey,
			PE.paDeKey,
			SUM(IT.itAmount) AS itAmount
			FROM dbo.HistItems IT 
			JOIN Runs RU ON It.itRuKey = RU.ruKey
			JOIN PayEmps PE ON IT.itEmKey = PE.paEmKey AND IT.itRuKey = PE.paRuKey
			JOIN GlSub ON GlSub.gsKey = IT.itGsKey
			WHERE RU.ruYear = 2015
			  AND GLSub.gsAccount = '4101'
			GROUP BY IT.itGsKey, PE.paDeKey) as Total
	ON PayEmps.paDeKey = Total.paDeKey

	LEFT JOIN 
	(SELECT IT.itGsKey,
			PE.paDeKey,
			SUM(IT.itAmount) AS itAmount
			FROM dbo.HistItems IT 
			JOIN Runs RU ON It.itRuKey = RU.ruKey
			JOIN PayEmps PE ON IT.itEmKey = PE.paEmKey AND IT.itRuKey = PE.paRuKey
			JOIN GlSub ON GlSub.gsKey = IT.itGsKey
			WHERE RU.ruYear = 2015
			  AND MONTH(RU.ruStartDat) IN (1,2,3)
			  AND GLSub.gsAccount = '4101'
			GROUP BY IT.itGsKey, PE.paDeKey) as JanMrt
	ON PayEmps.paDeKey = JanMrt.paDeKey

	LEFT JOIN 
	(SELECT IT.itGsKey,
			PE.paDeKey,
			SUM(IT.itAmount) AS itAmount
			FROM dbo.HistItems IT 
			JOIN Runs RU ON It.itRuKey = RU.ruKey
			JOIN PayEmps PE ON IT.itEmKey = PE.paEmKey AND IT.itRuKey = PE.paRuKey
			JOIN GlSub ON GlSub.gsKey = IT.itGsKey
			WHERE RU.ruYear = 2015
			  AND MONTH(RU.ruStartDat) IN (4,5,6)
			  AND GLSub.gsAccount = '4101'
			GROUP BY IT.itGsKey, PE.paDeKey) as AprJun
	ON PayEmps.paDeKey = AprJun.paDeKey

	LEFT JOIN 
	(SELECT IT.itGsKey,
			PE.paDeKey,
			SUM(IT.itAmount) AS itAmount
			FROM dbo.HistItems IT 
			JOIN Runs RU ON It.itRuKey = RU.ruKey
			JOIN PayEmps PE ON IT.itEmKey = PE.paEmKey AND IT.itRuKey = PE.paRuKey
			JOIN GlSub ON GlSub.gsKey = IT.itGsKey
			WHERE RU.ruYear = 2015
			  AND MONTH(RU.ruStartDat) IN (7,8,9)
			  AND GLSub.gsAccount = '4101'
			GROUP BY IT.itGsKey, PE.paDeKey) as JulSep
	ON PayEmps.paDeKey = JulSep.paDeKey

	LEFT JOIN GLSub
	ON Total.itGsKey = GLSub.gsKey
	AND JanMrt.itGsKey = GLSub.gsKey
	AND AprJun.itGsKey = GLSub.gsKey
	AND JulSep.itGsKey = GLSub.gsKey
	
	WHERE Runs.ruYear = 2015
		  AND GLSub.gsAccount = '4101'
	GROUP BY Departments.deName, GLSub.gsAccount, 
		Total.itAmount, JanMrt.itAmount, AprJun.itAmount, JulSep.itAmount
	ORDER BY Departments.deName, GLSub.gsAccount