HM Revenue and Customs (HMRC) have published a one-page guide for newly self-employed people to assist them in calculating their first tax bill.
When you start in self-employment, you do not get your first tax bill for a while, so it is important to give consideration to how much money to set aside as you go along. The guide contains a table to help you work out the approximate Income Tax (IT) and Class 4 National Insurance Contributions (NICs). However, HMRC stress that this is only a guide and that the exact amount of IT and Class 4 NICs due and payable can only be calculated once you have completed your Self Assessment tax return.
Further information on getting started in business and on IT and NICs is available on the Business Link website.