A 401(K) KIN is a type of retirement plan that allows individuals to save for retirement. The two most common types of 401(K) KINs are the Keogh Plan and the Individual Retirement Account (IRA). The Keogh Plan is a retirement plan designed for self-employed individuals or small business owners, while the IRA is a retirement plan available to all individuals. Both plans allow individuals to contribute pre-tax dollars to their retirement savings and defer taxes until they withdraw the funds.