Suppose your column data is in columns A thru E, and your totals are in
F. Insert a new column immediately to the left of your totals, so the
new blank column is F and the totals are in G. Set up the totals
formulas so the range includes the blank column; then when you insert a
new column to accommodate a new month, insert it to the left of the
blank column F. After the insert, F is the column for the new month,
the blank column will be G, and the totals range will still extend to
the blank column.