It's a bit of a cheat, but you can give the right appearance with conditional
formatting. Where your dates are in column A, put the formula

=DATE(YEAR(A2),MONTH(A2),1) etc. in column B.

Then conditionally format the cell in column B3 as follows

Cell Value is Equal To =B2

and set Font to White on that condition

Finally paste the format onto the rest of column B.


"Sarah (OGI)" wrote:

I have a list of dates in ascending order.

In another column, I want to summarise the dates according to month, but
only for the first instance of that month, i.e. for the first Jan date
listed, I want the adjacent cell to show 'January', but I don't want the word
'January' to show for all Jan dates.

Any ideas?