how do i use input parameters with criteria

I have a select query which is mainly made up of expressed columns based on
"IF" statements comparing the two table in the query then returning a value.
I have input paremeters based on a [Warehosue location], [Audit Start date]
and [Audit end date]. In which I have identifeid what to return in the event
any of these are null. This gives me eight rows of input parameter criteria.
Now I want to add criteria in one column to be 0. This column summates all
the other "IF" statement columns. Is there an easy way to do this? I am using
Access 2007.