The Standard Deduction has nothing to do with it. You might not owe regular income tax on your income if it is less than the Standard Deduction but you still owe self employment tax on a Net Profit.
So you paid a tax due on your original return? And you got a bill for more? Oh you have a Loss on Schedule C? Is the 4410 on Schedule 1 a loss with a minus sign or ()? Is the IRS disallowing your expenses?
