Let say we received the given date from text box:-
private void button1_Click(object sender, EventArgs e)
{
DateTime GivenDate = Convert.ToDateTime(textBox1.Text);
int GivenYear = GivenDate.Year;
for(int i=0; i<5; i++)
{
comboBox1.Items.Add(GivenYear + i + "-" + (GivenYear + 1 + i));
}
}