Higher earners who are affected by the recent changes in Child Benefit rules and have yet to register for self assessment have until the end of today, 21 January, to take action if they are to meet the filing deadline and avoid a potential penalty.

Individuals earning more than £50,000 - who are affected by the High Income Child Benefit Tax Charge introduced last year - must either opt to stop receiving payments or notify HMRC that they will file a tax return via the self assessment procedures.

Latest estimates from HMRC suggest around 100,000 people have failed to register for self assessment and could be at risk of receiving a penalty for failing to meet the 31 January deadline for online filing, the only option now open to them.

Lucy Brennan, partner in the Private Wealth group at Saffery Champness, said: 'This process takes time. Although registration can be done online, HMRC do not operate through email and so the required activation codes and Unique Taxpayer References need to be sent in the post. HMRC have stated that individuals need to start the process for electronic online filing by 21 January, so this is a real deadline for those that are not registered already with HMRC.'

Brennan is urging anyone affected by the changes who has not registered for self assessment to do so immediately, and also cautions that some taxpayers may unaware that they are liable for the charge.

'It is not just parents of children that are affected, it could affect an individual earning over £50,000 where they are living with a child and someone else is claiming child benefit for that child,' Brennan said.