W-2 Tax Analyzer Input the main boxes from your W-2 to see your effective withholding rates. JavaScript Required Box 1 (Wages) Box 2 (Federal Income Tax Withheld) Box 4 (Social Security Tax Withheld) Analyze Effective Federal Income Tax Withholding: 0% Effective Social Security Rate: 0% (Should be exactly 6.2% up to wage base)