Actually, I am not too proud to admit that solution stunk up the house! Not sure what I was thinking there.

This will be much faster, assuming a PRIMARY KEY consisting of id, cid and startdate of course.

SELECT id, cid, StartDate

,EndDate=CASE

WHEN DATEPART(year, StartDate) = DATEPART(year, GETDATE()) THEN NULL

WHEN DATEPART(year, EndDate) = DATEPART(year, StartDate) AND EndDate <> StartDate THEN EndDate

ELSE DATEADD(year, 1, DATEADD(year, DATEDIFF(year, 0, StartDate), 0))-1

END

FROM #table a

OUTER APPLY

(

SELECT TOP 1 StartDate-1

FROM #table b

WHERE a.id = b.id AND a.cid = b.cid AND a.startdate < b.startdate

ORDER BY b.startdate

) b(EndDate)

ORDER BY id, cid, StartDate;