Microsoft Word has a date field, but it's not easy to use in an expression. If you need to update dates in a document, use Excel to calculate the dates and then run a mail merge.

How To Automate a Table in Word Using Excel. As the world's leading business productivity suite, Microsoft Office provides many useful features including the ability to automatically display data ...

There are some functions in Excel that can be easily performed in Word. See which ones you can use.

If your source data is in Excel and has duplicates, run Power Query to remove those duplicates before running a Word mail merge.