Would this help?

WITH SampleData([EMPID],[EffectiveDate],[PrimaryRater], [PrimaryReviewer])

AS

( --This is sample data

SELECT '12345',convert(datetime,'10/10/2001'),'A12345', 'A67890' UNION ALL

SELECT '12345','07/12/2013','A12345', 'B67890' UNION ALL

SELECT '12345','08/18/2002','A12345', 'C67890' UNION ALL

SELECT '12345','07/17/1966','A12345', 'D67890' UNION ALL

SELECT '12345','01/01/1966','B12345', 'E67890'

)

--Solution starts here

,CTE AS(

SELECT EMPID,

PrimaryRater,

MIN( EffectiveDate) StartDate,

MAX( EffectiveDate) EndDate,

DENSE_RANK() OVER( PARTITION BY EMPID ORDER BY Min(EffectiveDate)) RN

FROM SampleData

GROUP BY EMPID,

PrimaryRater

)

SELECT c.EMPID,

c.StartDate,

c.PrimaryRater,

s.PrimaryReviewer,

ISNULL( c2.StartDate, GETDATE()) EndDate

FROM CTE c

JOIN SampleData s ON c.EMPID = s.EMPID

AND c.PrimaryRater = s.PrimaryRater

AND c.EndDate = s.EffectiveDate

LEFT

JOIN CTE c2 ON c.EMPID = c2.EMPID

AND c.RN = c2.RN - 1