This site explains how to perform vlookup on multiple criteria using an array
I modified the forumla slightly to provide a "0" response if one of the lookup values is blank, thus preventing a N/A# error
{=IF(R5="",0,(INDEX('Rate Table'!$F$5:$F$63,MATCH(A5&D5&R5,'Rate Table'!$B$5:$B$63&'Rate Table'!$E$5:$E$63&'Rate Table'!$A$5:$A$63,0)))}
The absolute key here is that you cannot just hit ENTER, you must hit ENTER+SHIFT+CTRL in order for excel to recognize this as an array formula. You do not enter the "squiggly" brakets, excel will do that automatically if the formula is entered correctly.
