401K has nothing to do with Social Security. You can have both a 401K and Social Security benefits because you are putting monies in both. If there was no 401K, how will that save Social Security? Actually, you will be worst off. For one thing, the 401K shields your monies from taxes until you take required minimum distributions at age 72 now. If there was no 401K, you would be paying higher taxes on those monies going to a 401K if it was all taxable. Still, it will not be going to the Social Security Trust Fund. Of course, you probably, would have salted those monies away in an Individual Retirement Account (IRA) if there was no 401K.