You usually have 60 days to file an appeal after receiving a denial notice, plus an extra five days to allow for mailing. For the most part, if you do not meet this deadline, you will have to begin again with a new application, which may mean that you will lose some back benefits. Whenever possible, make sure to appeal all denials within 60 days of the date on the notice.
However, sometimes the Social Security Administration will grant an extension of the deadline if it is found that you had “good cause” for missing the deadline. To argue that you had good cause, file the appropriate appeal and include a letter explaining why your request for review was untimely. If the SSA finds good cause for your delay in appealing, you will be given an extension.
Reasons that might constitute “good cause” for untimely filing of appeals include receipt of any communication from the SSA that inadvertently misled you by giving incorrect or incomplete information about when and how to request administrative review, or if you failed to understand the necessity of appealing timely. Good cause might also be found if you had any mental or educational limitations (such as not properly understanding English), or if you were physically prevented from filing an appeal (such as a hospitalization or seriously ill). If the SSA communications were lost in the mail that might provide a basis to argue there was good cause for missing the deadline.