Applying for Social Security before the mandated retirement age and/or while still working part-time can adversely affect the amount of the benefits to which your father is entitled.  If he's 63 now, he was born in 1945 (or thereabouts), for which the retirement age is 66.  In addition, he would have to advise Social Security whether he intends to fully retire or continue to work in some capacity.  Earnings can reduce his benefits.  Visit www.socialsecurity.gov  (and especially http://www.ssa.gov/pubs/10038.html) for more information and helpful fact sheets on your father's situation.