Question: I’m trying to figure out how to use conditional formatting to check if the date column is in sequential order and highlight a cell if it is not. Answer: Here is how you can create a conditional formatting rule which would highlight dates or numbers out of sequence. Assuming your first date is in A1 and the rest below them:
  • Select all dates in the range from A2 down
  • In conditional formatting, select the option to create conditional formatting based on a rule
  • Enter this formula =A2
  When you OK that rule you will see that all dates which are not in sequence compared to the previous one will be formatted Excel sample data showing the conditional formatting dialog and formula     I first published this answer on MrExcel forum