If the employee had railroad employment and employment covered by the Social Security Act in the same year, both railroad retirement and social security taxes may have been deducted from the employee's earnings. Excess taxes that were deducted from the employee's earnings in the years between 1950 and 1974 can be refunded by the RRB. Excess taxes that were deducted for years after 1974 must be refunded by the Internal Revenue Service.