I don't get it. Could you please post sample data and expected results? Check the article linked on my signature to guide you.

Your description and the results seem to match, but I might be misunderstanding the whole problem.

This is what I used to test.

WITH CTE(col1, col2) AS(

SELECT 'abc' col1, 'bbc' col2 UNION ALL

SELECT 'nbc' col1, 'abc' col2 UNION ALL

SELECT NULL col1, NULL col2 )

SELECT *

FROM CTE

WHERE ISNULL( col1, '') NOT IN ('abc', 'def', 'ghi')

OR (col2 is null or isnull(col2,' ') NOT IN ('abc', 'def', 'ghi'))