Self-employment income is money you earn working for yourself — as a freelancer, independent contractor, or business owner. It's reported on Schedule C and is subject to both income tax and self-employment tax (15.3%). You can deduct legitimate business expenses to reduce the amount you owe. If you expect to owe $1,000 or more in taxes, you'll need to make estimated quarterly payments. Keeping good records all year makes tax time much easier.