<input name="ActivateBtn" type="submit" class="btn btn-primary" value="Activate" onclick="opendatedialog()" />

<script>
    function opendatedialog() {
        $("#datepickerdialog").dialog({
            height: 300,
            width: 500,
            modal: true,
            resizable: false,
            buttons: {
                "OK": function () {
                    var viewUrl = '@Url.Action("Activate", "User")';
                    $.post(viewUrl, new { startDate: $('.datepickerstart').val(), endDate: $('.datepickerend').val() });
                    $(this).dialog("close");
                    return true;
                },
                "Cancel": function () { $(this).dialog("close"); return false; }
            },
            open: function () {
                $(this).siblings('.ui-dialog-buttonpane').find("button:contains('OK')").focus();
            }
        });
    }
    $(function () {
        $('.datepickerstart').datepicker(
            {
                minDate: 0,
                dateFormat: 'yy-mm-dd'
            }).datepicker("setDate", "0");
        $('.datepickerend').datepicker(
            {
                minDate: 0,
                dateFormat: 'yy-mm-dd'
            }).datepicker("setDate", "2099/12/31");
    });

[HttpPost]
public ActionResult Activate(DateTime startDate, DateTime endDate)
{
    //TO DO
    return RedirectToAction("Index");
}