There are a few ways to autofill dates in Excel. The easiest way is to type in the first date in the cell, then hold down the Ctrl key and drag the mouse over the cells that you want to fill in with the same date. Excel will automatically fill in the dates for you. Another way to autofill dates is to type in the first date in the cell, then type in the formula =DATE(year,month,day) in the cell below it. Excel will automatically fill in the dates for you.