This should do it entered into AA4:

=IF(AND(C4<2005,Q4=2005),U4,IF(AND(C4=2005,Q4=2005 ),J4+U4,IF(AND(C4=2005,Q4<2005),J4,"None
of these")))

If the combinations of C4 and Q4 are not any that you state, then you
will get the text "None of these" - you might want to set this to zero
or some other value.

Hope this helps.

Pete