how to use the keyword `VALUES` in an `IN` statement?
One option is to reference the VALUES clause just as you would if it were materialised.
INSERT INTO [APCore].[usr].[userBusinessArea]
           ([businessAreaID]
           ,[userID])
SELECT 
    businessAreaID,
    userID
FROM (
     VALUES
           (21, 368), 
           (21, 227419) ,
           (21, 99906), 
           (21, 140470)
) v (businessAreaID, userID)
WHERE v.userID NOT IN (368,227419,99906,140470);

See also the examples in the docs
Try it on db&lt;&gt;fiddle