Line 6 is for any W2 wages you receive which are subject to income tax when you file your 1040, but already have social security and medicare taxes and potentially federal and state withholding taken out.u00a0 Self employment income is subject to self employment tax plus income tax and thus the worksheet makes a distinction between what you earned as a self employed person (line 1) vs what you earn as an employee (line 6), because the nature of your employment earnings will impact how much estimated tax you should be paying in.