Hansen (P) met with Don Connelly, a field representative for the Social Security Administration and orally inquired if she was eligible for mother's insurance benefits. Connelly erroneously told P that she was not. P then left the SSA office without having filed a written application. Only written applications satisfy the filed application requirement of the act and the regulations that interpret the act. The SSA's Claims Manual, instructs field agents to advise applicants of the advantages of filing written applications and to recommend to those uncertain about eligibility to file. Connelly never followed those directions and did not recommend to P that she file a written application. P eventually filed an application and got the benefits. P then asked for the benefits to the date of her original meeting with Connelly based on principles of estoppel.