hi, thank you bob.. you have got me on the right track (i hope!)
basically all i need to do now is the following.
i want this:
=Sum(IIf([fkAccountTypeID]=2,Nz([JobTdCp],0)+(IIf([fkAccountTypeID]=2,Nz([JobTdFare],0)+(IIf([fkAccountTypeID]=2,Nz([JobTdExtra],0)))))))
minus this...