If you are one of the thousands of people claiming child benefit, and have been notified by HMRC that you will have reduced child benefit payments due to your earnings, you will generally have to complete a self assessment tax return.
A self assessment tax return is used to declare your income and tax and needs to be completed usually on line by a set deadline each tax year.
HMRC state that if you or your partner have earnings over £50,000 and you keep claiming child benefit, then your income and child benefit payments will typically have to be completed on a self assessment tax return.
If you do not already complete a self assessment tax return you will have to register with HMRC, who will then notify you of what to do and when. Be aware that penalties are imposed if your self assessment tax return is not submitted on time. You can either complete your self assessment on paper or online. Different deadlines apply to each method of processing.