20 CFR 416.1404: Notice of the initial determination.

(a) We will mail a written notice of our initial determination to you at your last known address. The written notice will explain in simple and clear language what we have determined and the reasons for and the effect of our determination. If our determination involves a determination of disability that is in whole or in part unfavorable to you, our written notice also will contain in understandable language a statement of the case setting forth the evidence on which our determination is based. The notice also will inform you of your right to reconsideration. We will not mail a notice if the beneficiary's entitlement to benefits has ended because of his or her death.

(b) If our initial determination is that we must suspend, reduce or terminate your benefits, the notice will also tell you that you have a right to a reconsideration before the determination takes effect (see § 416.1336).