Query: Monthly billing on specific day of month

Just a quick challenge.
Had a minor brain overload last Friday, eventually came up with (I think) a sub-optimal query ...
Basic scenario is that I want a billing event to happen on the monthly anniversary of a event, and want a single SQL statement that, given the original and current date, will tell me whether I should be billing on that day.
Problem is that e.g. if original date if 31-Jan-07 then I should bill on the 28-Feb-07. Moreover if the original date is 28-Feb-07 then I should bill on 28-Jan-07. However, the when the original date is 28-Feb-07 the Oracle months_between function isn't suitable as it returns 1 for both the 28-Mar-07 and 31-Mar-07, as follows:

select months_between(to_date('28-JUL-2007'),to_date('28-FEB-2007')) m1
,      months_between(to_date('31-JUL-2007'),to_date('28-FEB-2007')) m2
from   dual;

        M1         M2
---------- ----------
         5          5

1 row selected.

Okay, so here's my solution ... with a loop to test for a year. Anyone got a better alternative to the core query?

set serverout on size 1000000
declare
 org_date date := '28-JAN-03';
 cur_date date := '01-JAN-04';
 l_status varchar2(1);
 l_count number := 0;
 l_pays  number := 0;
begin
 while true loop
  l_count := l_count+1;
  begin
   select 'Y' yes
   into   l_status
   from   dual
   where 
      (
        (to_number(to_char(org_date,'DD')) <= 28 and
         to_number(to_char(org_date,'DD')) = to_number(to_char(cur_date,'DD'))
        )
        or
        ( to_number(to_char(org_date,'DD')) = 29 and
          ( to_number(to_char(org_date,'DD')) = to_number(to_char(cur_date,'DD'))
            or
            ( to_number(to_char(last_day(cur_date),'DD')) < 29 and
              to_number(to_char(last_day(cur_date),'DD')) >= 28 and
              cur_date = last_day(cur_date)
            )
          )
        )
        or
        ( to_number(to_char(org_date,'DD')) = 30 and
          ( to_number(to_char(org_date,'DD')) = to_number(to_char(cur_date,'DD'))
            or
            ( to_number(to_char(last_day(cur_date),'DD')) < 30 and
              to_number(to_char(last_day(cur_date),'DD')) >= 28 and
              cur_date = last_day(cur_date)
            )
          )
        )
        or
        ( to_number(to_char(org_date,'DD')) = 31 and
          ( to_number(to_char(org_date,'DD')) = to_number(to_char(cur_date,'DD'))
            or
            ( to_number(to_char(last_day(cur_date),'DD')) < 31 and
              to_number(to_char(last_day(cur_date),'DD')) >= 28 and
              cur_date = last_day(cur_date)
            )
          )
        )
      );
   dbms_output.put_line('Billing org_date='||org_date||' cur_date='||cur_date);
   l_pays := l_pays + 1;
  exception
  when no_data_found then
   null;
  end;
  if l_count > 366 then
   exit;
  end if;
  cur_date := cur_date + 1;
 end loop;
 dbms_output.put_line('Payments = '||l_pays);
end;
/

Comments more than welcome!