5
It's not so hard to do this transformation. Step by step:
DATEADD(DAY
, ISNULL(a.[due_days], 30) + 30
, [dbo].[CalcDate]([type], date1, date2, date3, date4, NULL)
) < GETDATE()
means:
[dbo].[CalcDate]([type], date1, date2, date3, date4, NULL)
+ (ISNULL(a.[due_days], 30)...