<div class="row">
<div class="input-group col-md-6">
<div class="form-group ">
<asp:Label runat="server" ID="Label1" ClientIDMode="Static" Style="margin-left:15px" Text="GL Code" Font-Size="20px" Class="text-bold lblcaption"></asp:Label>
<asp:TextBox runat="server" Style="margin-left:15px" ID="DrpIncomeCode" ClientIDMode="Static" CssClass="form-control"></asp:TextBox>
<div class="input-group-append">
<button class="btn btn-outline-secondary" id="btnincode" style="font-size:20px; width:70px; height:36px" runat="server" clientidmode="Static">Search</button>
</div>
</div>
</div>
<div class=" col-md-6">
<div class="form-group">
<asp:Label runat="server" ID="Label2" ClientIDMode="Static" Text="GL Description" Font-Size="20px" Class="text-bold lblcaption"></asp:Label>
<asp:TextBox runat="server" ID="txtIncomeDesc" ClientIDMode="Static" CssClass="form-control"></asp:TextBox>
</div>
</div>
</div>
View the attached image
Please ensure that the gap is closed.