Hi,
Following code may help you:-
int icurrMonth = DateTime.Now.Month;
string sYear="";
if (icurrMonth < 4)
{
sYear = (DateTime.Now.Year - 1).ToString();
}
else
{
sYear = DateTime.Now.Year.ToString();
}
txtBox.Text = "31-03-" + sYear;
Note : 1. Replace "txtBox" with your "TextBox ID"
2. Replace "DateTime.Now" with "Date of Joining"