Maybe or maybe not. Will you still have the W2 income? You can increase the W2 withholding to cover any self employment tax. If you owe too much on your tax return you may have to pay a penalty for not paying in enough evenly during the year.
Self Employment tax (Scheduled SE) is generated if a person has $400 or more of net profit from self-employment. You pay 15.3% SE tax on 92.35% of your Net Profit (If it is greater than $400). The 15.3% self employed SE Tax is to pay both the employer part and employee part of Social Security and Medicare (FICA). So you get social security credit for it when you retire.
