Self-employment is working for one's self. Self-employed people can also be referred to as a person who works for himself/herself instead of an employer, but drawing income from a trade or business that they operate personally.Self Employed Tax is a tax consisting of Social Security and Medicare taxes primarily for individuals who work for themselves. It is similar to the Social Security and Medicare taxes withheld from the pay of most wage earners.You figure self-employment tax (SE tax) yourself using Schedule SE (Form 1040). Social Security and Medicare taxes of most wage earners are figured by their employers. Also you can deduct half of your SE tax in figuring your adjusted gross income. Wage earners cannot deduct Social Security and Medicare taxes.If you're self-employed, you are responsible for paying your own tax and National Insurance contributions. You'll need to keep business records and details of your income so you can fill in an annual Self Assessment tax return.