select          dd.YR_MONTH,
                a.dep_code,
                a.div_code,
                d.dep_name,
                actions_assigned = isnull(count(a.action_id),0)
from            DimDate dd
Left outer join sr_assigned_to a
on              (assign_date =[DATE] or assign_date is null)
Left outer join sr_dep_codes d
on              (d.dep_code = a.dep_code or d.dep_code is null)
and             (d.div_code = a.div_code or d.div_code is null)
where           [date] between DATEADD(m,-13,DATEADD(mm, DATEDIFF(m,0,GETDATE()), 0))
                          and  DATEADD(d,-1,DATEADD(mm, DATEDIFF(m,0,GETDATE()),0))
group by        a.dep_code,
                a.div_code,
                d.dep_name,
                dd.YR_MONTH