Common Myths Regarding Self-Employment

"I will pay lower taxes as a self-employed person than earning the same amount as an employee".
When you are self-employed, you will still have Tax and National Insurance to pay. These are mostly based on the profit your business makes each year. In general, you will pay similar taxes as you would if you were employed, on a salary equal to the profit your business makes.

See Taxes Payable as a Self-Employed Person.

"I only expect to earn £2,000 per year and someone told me I don't have to declare small amounts".
Since the introduction of HM Revenue and Customs' Trading Allowance, trading income of up to £1,000 per tax year may not be required to be declared on a tax return.  However, this depends on meeting the criteria for use of the Trading Allowance, and your other income.  If your trading income is more than £1,000 per tax year, you will need to register for Self-Assessment, even if you only expect to make small profits (or even losses) and even if you think you will have no Tax or National Insurance to pay.

See Registering with HM Revenue and Customs.

"Someone has told me I can choose to become self-employed, working as such for my current employer, and my employer has said they will pay me more if I do this".
Your employment/self-employment status is not a personal choice, nor the choice of your employer; it is a matter of fact, based on factors determined by HM Revenue and Customs' rules.

See Self-Employed or Employed?