How do you complete a date formula?

[goaltender]

I am trying to input a formula so that when a date is entered it automatically changes another cell date. ie. I have three column headers, date last tested, date due and date test completed. When the "date test completed" is entered I want it to automatically update the "date last completed" column and add 12 months to this and automatically change "date due" to the updated date. If anyone can understand and help it would be appreciated. Thanks.

[Rutgers_Excels]

Try this (assuming the cell you want to add 1 year to is A1)

=DATE(YEAR(A1)+1,MONTH(A1),DAY(A1))