Ok, i've searched and found something very similar to what I want.
Now, of the code:
=Right(Date(),2) & Right(NZ(DMax("[EventNo]","[tbl_EmgCalls]","Left([EventNo],2)='" & Right(Date(),2) & "'"),"9900000")+1,5)
so, the table involved is tblJobregister and the field is Job No set out as last 2...