Following your requirements, this could work:

=IF(H4<DATE(2007,1,9),"",IF(I4<$A$2,"",IF(AND(J4<H 4,K4H4),"EX",IF(AND(ISBLANK(K4),J4<H4),"EX",""))) )

HTH.

The formula in cell L4 needs to account for the following conditions:

- If the date in Column H is earlier than 10/01/07, then put a blank
in Cell L4. Otherwise, go to next condition
- If the date in Column I is earlier than today's date in Cell A2,
then put a blank in Cell L4. Otherwise, go to next condition.
- If today's date in Column J is earlier than the date in Column H
AND if the date in Column K is later than the date in Column H, then
put "EX" in Cell L4. Otherwise, go to the next condition.
- If Column K is blank AND if the date in Column J is earlier than
the date in Column H, then put "EX" in Cell L4.