How to build a nested function and formula in Microsoft Excel to use in conditional formatting to highlight dates that have gone over one month from today where today dynamically changes based on today's date. This video shows you how to use the formula within the Excel's conditional formatting function. The functions used in this video include the secret DATEDIF function, IFERROR function, VALUE function, TODAY function, and Concatenation using the ampersand. Conditionally Formatting Dates help you with your projects and planning.