Your data in the first column you are looking up against will need to be ordered
in Descending order, and you will need to use INDEX and MATCH together, with -1
as the final argument in the MATCH function, eg:-
Assuming your VLOOKUP formula was as follows:-
=VLOOKUP(D1,$A$1:$B$10,2) with the value being looked up being in D1.
The data for this in Col A would be ordered in Ascending order. To get the next
highest value, you need to resort the data based on Col A in Descending order,
and the formula would now look like this:-
=INDEX($B$1:$B$10,MATCH(D1,$A$1:$A$10,-1))
Note, the $ signs aren't really necessary, but I like em.