How do I figure out how much money I owe for self-employment tax this year and do they directly take it out of my refund that I will receive this year?

Self employment tax is calculated based on 15.3% of your net business income. A portion is for social security and a portion is for Medicare. If your income was more 127,200 dollars in 2017, and net business income over that amount will have a self employment tax of 2.9% (social security tax is only charged on the first 127,200 dollars of earned wages, or self employment income).

TurboTax will accurately calculate your self-employment tax and apply it on your tax return. If there is a refund, the self-employment tax would be taken out of the refund. Otherwise, you would have to pay the self-employment tax out of pocket.