No, you can only be charged money (we assume that's what you mean when you write "charged") IF you had agreed to that term or condition of employment prior to being hired. It does not matter if they made it a new policy if you were never told of it and did not agree to it when you were hired. One party (i.e. the employer) cannot unilaterally (on its own) impose an obligation (to pay something) on another party (you) without the second party's consent or agreement.