change sql statement and make it simple

[Quoted] I have the following query....it checks which half of the year is last month..
[Quoted] and then if it is first half it returns 1-Jan-2000 and if it is second half [Quoted] 1-July-2000

is there a way to get rid of the in-line view and do it in one go...and not [Quoted] use a function on custmer contact_date too...

any ideas...
thanks

select customer_id
from customers a,

     (select trunc(add_months(sysdate,-1),'year') begin_date
      from dual
      where to_number(to_char(add_months(sysdate,-1),'mm')) between 1 and 6
      union
[Quoted]       select add_months(trunc(add_months(sysdate,-1),'year'),6) begin_date
      from dual
      where to_number(to_char(add_months(sysdate,-1),'mm')) between 7 and 12
      ) b