In this article I will explain with an example, how to make CheckBox ReadOnly in ASP.Net with C# and VB.Net.
By default, ASP.Net CheckBox cannot be made ReadOnly and hence using JavaScript it is made Non-Clickable.
HTML Markup
The following HTML Markup consists of an ASP.Net CheckBox.
<asp:CheckBox ID="chkPassPort" Text="Do you have a Passport?" runat="server" />
Making CheckBox ReadOnly in ASP.Net
Inside the Page Load event, the Client Side onclick attribute of the CheckBox is set with JavaScript return false statement.
Thus when the CheckBox is clicked, it does not change the state of the CheckBox.
protected void Page_Load(object sender, EventArgs e)
    chkPassPort.Attributes["onclick"] = "return false";
Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load
    chkPassPort.Attributes("onclick") = "return false"
End Sub
Make CheckBox ReadOnly in ASP.Net