overhead of varchar(max) columns with small data

Question

As part of a bulk load of data from an external source the stageing table is defined with varchar(max) columns. The idea being that each column will be able to hold whateve

Answer 1

Well I want to say that there shouldn't be that big an overhead because i don't think that sql automatically assigned an alloted amount of data for nvarchar, and instead only allots what is needed for what is inserted, but i don't have naything to prove or back up that idea.