HMRC has published a policy paper and draft legislation that proposes a statutory obligation on taxpayers to correct errors in past tax returns. It is proposed that this new legislation should feature in Finance Bill 2026/27 and would come into effect on a day to be appointed. The draft legislation is presently out for consultation until September and so may change.
The same draft legislation also covers a proposed power for HMRC to issue correction notices where it has reason to suspect an error in a document that can be corrected. This note concentrates on the proposed obligation to self-correct.
The genesis of this proposal is the HMRC Tax Administration Framework Review in 2024/25. Responses to that review were published in April 2025 and one of the proposals that the Government said it would take forward was approaches to taxpayer self-correction. This current proposal is presented as part of an approach to modernise and simplify tax administration.
To date the precise legal (as opposed to professional or ethical) obligation to correct the position when a taxpayer discovers a mistake in a tax return already submitted to HMRC may have been unclear. This proposal intends to address that situation.
Under the new proposal, when a person “becomes aware” of an inaccuracy in a return that has led to an underpayment of tax and, at that time, the inaccuracy may be corrected either by the taxpayer themself or HMRC in some way, the taxpayer must either correct the inaccuracy themselves if they are able to do so or inform HMRC of the inaccuracy. Section 118(6) TMA 1970 is amended so that failure to comply with the obligation to correct will lead to the inaccuracy being treated as deliberate on the taxpayer’s part. Such treatment would impact upon HMRC’s assessing powers, the quantum of any penalty for non-compliance and open the possibility of ‘naming and shaming’ in connection with what may previously have been an innocent error.
It should be noted that the draft legislation is not restricted to a particular type of inaccuracy or error. The governing concept is an “inaccuracy in relation to which Condition 1(2) of [Schedule 24 FA 2007] is satisfied”. So, the test proposed is: does the inaccuracy “amount to or lead to (i) an understatement of a liability to tax, (ii) a false or inflated statement of loss or (iii) a false or inflated claim to repayment of tax.” Consequently, a wholly innocent mistake is within scope.
The trigger for the obligation to self-correct is that the taxpayer becomes “aware” of the inaccuracy. The concept of ‘becoming aware’ is not unknown in tax legislation but is a term that has an inherent vagueness of meaning. Actual knowledge is clearly within scope but what about the jurisprudence on ‘blind eye knowledge’? Is a decision not to look at what the taxpayer suspects might be a problem within scope?
There are a number of questions and concerns with this proposed legislation. For example;
• How does this proposal interact with the declaratory nature of judicial decisions? Does a return that was submitted based upon a particular view of the law become inaccurate and liable to correction when a subsequent judicial decision overturns that view of the law? How does the taxpayer deal with conflicting decisions as a case proceeds on appeal? Suppose the initial view of the law was arguably “in accordance with the practice generally prevailing at the time when it was made”?
• Precisely when does the taxpayer “become aware” of the inaccuracy so as to become subject to the obligation to correct? Suppose that the taxpayer is not an individual?
Hopefully these and other questions will be answered by the current consultation on the draft clauses. However, it does seem likely that some provision relating to an obligation to self-correct will appear in next year’s Finance Bill. Taxpayers should be aware of this upcoming new obligation.
Should you wish to discuss this Insight, please contact:
Iain MacWhannell, Partner in our Tax Disputes Team:
imw@jha.com
+44 (0)20 7851 8888
Steve Bousher
*The class of documents potentially within the new obligation is wider than simply tax returns. The class includes all documents of types that fall within paragraph 1(4) of schedule 24 Finance Act 2007. This note refers simply to ‘returns’ as a convenient shorthand.
