You can insert a date or time field into a document that automatically updates every time you open the file. You can also keep the date static (that is, unchanging) if you like.
Click where you want to insert a date.
Click the Insert tab.
Click the Insert Date and Time button.
Word opens the Date and Time dialog box; click a format for the date or time.
Click OK.
The current date and time are added.
Tip
Automatic Update If you want the date or time to update automatically, make sure you click the Update Automatically check box in the Date and Time dialog box.