Many freelancers land their first big month — say $8,000 in invoices — and feel like they made $8,000. They did not. After self-employment tax, income tax, and whatever they forgot to track for expenses, the real number is closer to $5,200. And if they skipped a quarterly payment? Add an IRS penalty on top. This is not a rare situation. It is the default experience for solo workers in the US. Here is the math most people learn the hard way. The Two Tax Hits Nobody Warns You About When you are employed, your employer pays half of your Social Security and Medicare tax. When you are self-employed, you pay both halves. That is 15.3% on your net self-employment income, on top of regular income tax.…