string month = DateTime.Today.Month.ToString();
if (DateTime.Today.Month < 10)
{
    month = "0" + month;
}
string day = DateTime.Today.Day.ToString();
if (DateTime.Today.Day < 10)
{
    day = "0" + day;
}

string dateCorrect = String.Format("{0}.{1}.{2}", DateTime.Today.Year, month, day);

string dateDue = "";
if (transferFields.DueDate.SelectedDate.HasValue)
{
    var dateDuearr = transferFields.DueDate.Value.Split(' ')[0].Split('.');
    dateDue = dateDuearr[2] + '.' + dateDuearr[1] + '.' + dateDuearr[0];
}
else {
    dateDue = dateCorrect;
}