The above documents are important to maintain for several purposes. First of all, some of these items may need to be included with an application or petition to change status or at the time of filing an extension of status with a different employer. Although organization experts will advise you to trash documents that do not appear relevant in the immigration context, it is better to keep them in a file. For example, if one is falling out of status, the fact that the receipt notice indicates that the filing for change or extension of status occurred prior to the expiration of the present status is sometimes the only proof of not having fallen out of status, even if INS takes several months to adjudicate a case. In such a case, the approval notice could be misleading so the receipt notice may come in handy.
Every case is different.
A person who may have difficulty proving maintenance of status should consult with an attorney. P.C. More Stuff. . . .