I have a drop down list which has 3 items in it, i also have two Textboxes, Textbox1 and Textbox2. I want that when I select item1 from Dropdownlist and enter a date in Textbox1, The date in Textbox2 should be changed to 3years ahead of the date in Textbox1. Similarly when i select Item2 in dropdownlist and enter a date in Textbox1 the date in textbox2 should be automatically changed to (Textbox1 date+5years). I have the date in MM/DD/YYY format. Any ideas how to achive it using C# code. I know that I can use a stored procedure for this but I want to accomplish this using C# code.