FL57: line 57 in Federal Tax Form 1040 FL37: line 37 in Federal Tax Form 1040 SL24: line 24 in State Tax Form 540 B4: Box 4 in W-2 (Social Security Tax Withhold) B6: Box 6 in W-2 (Medicare Tax Withhold) B14: Box 14 in W2 (State Disability Insurance)
Federal Income Tax: FL57 / FL37 * 100 Federal Payroll Tax: (B4 + B6) / FL37 * 100 State Income Tax: SL24 / FL37 * 100 SDI: B14 / FL37 * 100
Your payroll tax rate calcuration becomes a little bit more complicated if you changed jobs last year and payroll tax withhold exceeded the maximum payroll tax.