An increase in the average retirement age from 64 to 68 would save about 20 percent in social security payments since the average number of years in retirement would be cut by about 20%. Similarly, an increase in retirement age to 70 would save about 25 percent in social security retirement benefits. Either change would also add significantly to revenue from social security taxes since workers would be employed for several additional years. Therefore, such increases in age of eligibility for social security benefits would go a long way toward solving the looming social security financial “crisis.”
More on this issue in The Becker-Posner Blog.