How to: Get and Set a CheckBox Web Server Control Value Programmatically
You can programmatically read or set the value of a CheckBox Web server control.
If you are working with a CheckBoxList control, the procedure for getting and setting the value of a check box is different. For details, see How to: Determine the Selection in List Web Server Controls.
To get or set CheckBox Web server control selection
Testing the value of a check box does not tell you if the user changed the value of the control, only if it is selected.
In the following example, if the check box chkCanWeSendEmail is not selected, the check box chkSendInHTMLFormat is automatically cleared as well.