The UK tax year is 6 April to the following 5 April. So the tax year 2011/12 ended on 5 April 2012.
You will need to complete a self assessment tax return if you are self employed or a limited company director.
Click here to read our free guide on starting a business and registering with HMRC (opens in a new window).
Although the deadline is 31 January for e-filed returns, we recommend that you complete your tax return and submit it to HMRC as early as possible. Click here to download a useful pdf tax return checklist.
A self employed person will pay both income tax and class 4 national insurance (NI) on their profits plus income tax on any other income and capital gains tax on any relevant capital gains in the tax year.
Read more about Planning for your self assessment tax bill