 <p>You cannot make change event just by setting value from javascript. Here is a sample by using trigger.</p> <pre><code> &lt;script&gt; $(document).ready(function () { $(".tbAdd_Sowner").on('change', function () { var owner = $('.tbAdd_Sowner').val(); $('.tbAdd_Sphone').val(owner); }); $(".aGetID").on('click', function () { var tbOwner = $('.tbAdd_Sowner'); var hidden1 = $('.Hidden1'); var hidden2 = $('.Hidden2'); var hidden3 = $('.Hidden3'); GalModalTOCCDialog(hidden1, tbOwner, hidden2, hidden3); }); function GalModalTOCCDialog(Hidden1, tbAdd_Sowner, Hidden2, Hidden3) { $(tbAdd_Sowner).val(' ').trigger('change'); } $('.tbAdd_Sowner').change(function () { $(this).removeAttr('disabled'); }); }); &lt;/script&gt; </code></pre> <p>Here is your code, removing those validators</p> <pre><code>&lt;table&gt; &lt;tr&gt; &lt;td align="right"&gt;Secondary Owner &lt;/td&gt; &lt;td&gt; &lt;input id="Hidden1" type="hidden" value="1" class="Hidden1" /&gt; &lt;asp:TextBox ID="tbAdd_Sowner" OnTextChanged="tbAdd_Sowner_TextChanged" CssClass="tbAdd_Sowner" AutoPostBack="true" runat="server" Enabled="false" &gt;&lt;/asp:TextBox&gt; &lt;input id="Hidden2" type="hidden" class="Hidden2" /&gt; &lt;input id="Hidden3" type="hidden" class="Hidden3" /&gt; &lt;a href="javascript:void(0)" id="aGetID" class="aGetID" &gt;Get User ID&lt;/a&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr&gt; &lt;td align="right"&gt;Secondary Owners&lt;/td&gt; &lt;td&gt; &lt;asp:TextBox ID="tbAdd_Sphone" runat="server" CssClass="tbAdd_Sphone" &gt;&lt;/asp:TextBox&gt; &lt;/td&gt; &lt;/tr&gt; &lt;/table&gt; </code></pre> <p>Server side. </p> <pre><code>protected void tbAdd_Sowner_TextChanged(object sender, EventArgs e) { tbAdd_Sowner.Text = "123"; } </code></pre>