Thana Prasongsin / Getty Images When you work for yourself, you're responsible for paying taxes that an employer would normally handle for you. Key Takeaways When you're self-employed, you pay 15.3% in Social Security and Medicare taxes—double what employees pay, because there's no employer to cover half. Tax payments are due quarterly. Missing them triggers IRS penalties that can add up fast. Starting a business sounds exciting until you think ahead to the taxes you might pay. Then the anxiety kick ...