When you are self-employed you are not having tax withheld from your paychecks nor are you paying Social Security and Medicare, so you have to pay all of that yourself at tax time unless you pay quarterly tax to keep your tax liability lower at tax time. You most likely had tax withheld from your W-2 job and were getting a refund until you added the untaxed additional income. Did you prepare a Schedule C for your business expenses? You are posting from Premier--not Self-Employed. You need Self-Employed to prepare a schedule C for business expenses.
https://ttlc.intuit.com/community/self-employed/help/what-is-the-self-employment-tax/00/25922
https://ttlc.intuit.com/questions/2902389-why-am-i-paying-self-employment-tax
https://ttlc.intuit.com/questions/1901340-where-do-i-enter-schedule-c
https://ttlc.intuit.com/questions/3398950-what-self-employed-expenses-can-i-deduct
https://ttlc.intuit.com/questions/1901110-do-i-need-to-make-estimated-tax-payments-to-the-irs
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
