“Do I need to complete a tax return?” should be a simple question. But a combination of HMRC’s (non-statutory) self-assessment criteria, outdated legal obligations and various measures intended to simplify matters by removing specific groups from self-assessment have resulted in a confusing gap between what the law says about who needs to file a tax return and who HMRC wants to register for self-assessment.

Last year, ATT technical officer Helen Thornley wrote a note for the British Tax Review seeking to highlight how that gap has arisen, and the potential problems with proposals to remove more individuals from self-assessment via new online services for those with small amounts of trading or property. 

As the government seeks to reduce the self-assessment population further, we are concerned that the current approach of allowing HMRC to set its own administrative criteria for specific groups and then designing services around them is confusing, undermines taxpayer responsibility and creates challenges for agents supporting taxpayers not in self-assessment. 

It is now time to ask who should we be asking to complete a tax return in the first place?  

Any new approach should ensure that the criteria for entry into self-assessment aligns with the point at which tax starts to be paid, is consistent between income sources to avoid confusion, and accompanied by clear HMRC guidance which—crucially—actually reflects the individual’s legal obligations. 

We are grateful for the publishers for allowing us to share the full note on the ATT website. 

This material was first published by Thomson Reuters, trading as Sweet & Maxwell, 5 Canada Square, Canary Wharf, London, E14 5AQ, in the British Tax Review as Do I need to complete a tax return?: recent changes to self-assessment [B.T.R. 2025, No.4, 446-457] and is reproduced by agreement with the publishers.