Conditional formatting gives you the option of formatting cells based on a date occurring "yesterday," "in the last 7 days,"last week" and "last month."

However, I need to create a formula to format cells older than today (yesterday) going back 12 months. How would I do this?

Thanks!

Hi namedujour

Assuming your data that you want apply the conditional formatting to, is in column A.
Select the column or the range of cells you wish to apply the formatting. Home tab > Conditional Formatting > New rule > Use a formula etc > Use the formula below in the box "Format values where this formula is true: > Apply the required formatting > OK

=AND($A1<>"",$A1<DATE(YEAR(TODAY())-1,MONTH(TODAY()),DAY(TODAY())))