If the figures to conditionally add are in column B, and the dates are in A,
=SUMIF(A:A,"=" & TODAY()-365,B:B) would add up all the values from the past
366 days (including the current day). Use that anywhere except in columns A
or B (in A or B you'll get a circular reference).

"Kevbro7189" wrote:

I want to add up numbers that only happened within the last 12 months from
the current date. I do have a column with the date I want to reference to.