Why does jQuery not see a checkbox has been auto checked?

I have some jQuery checking to see when a human clicks a check button but if the page loads with the button marked as checked already, the jQuery doesn't work.

    $ (function(){
        var requiredCheckboxes = $('.options :checkbox[required]');
        requiredCheckboxes.change(function(){
            if(requiredCheckboxes.is(':checked')) {
                requiredCheckboxes.removeAttr('required');
            } else {
                requiredCheckboxes.attr('required', 'required');
            }
        });
    });

What I need this to do is if the checkbox is already checked, it removes the required attribute. Why is it not working when a variable is posted to the page and PHP adds checked="checked" to the input?

Thanks!