If the date is in cell a2 highlight the area you want to change and go to Format - Conditional Formatting. Change Condition 1 to Formula is and enter =(NOW()-$A2)>45 Click Format and pick red. Click Add >> and do as above with =(NOW()-$A2)>30 and pick yellow. Make sure that there is a $ only before the A and not the number as when you copy it down the rows the row number will change to match.