In Tinkler v HMRC [2021] UKSC 39, the Supreme Court examined the conditions for estoppel by convention, finding that an agents action in complying with an enquiry notice rendered a tax enquiry and a subsequent issued closure notices valid, even though the original enquiry notice was invalid. 

Mr Tinkler Appealed on the preliminary issue of whether the enquiry had been validly opened, if not, the closure notices would also be invalid. The two primary issues in the case were:

The First Tier Tribunal found:

Mr Tinkler appealed (and HMRC cross-appealed) to the Upper Tribunal (UT) who found:

Mr Tinkler appealed to the Court of Appeal (CoA) who reversed the UT decision finding that:

HMRC appealed to the SC on the estoppel by convention issue who found:


This case highlights the importance of checking enquiry notices for their validity before engaging with HMRC. The actions of the taxpayer and their agent rendered what would otherwise have been an invalid enquiry valid.

Pulling such an argument out of the hat at a later date is unlikely to have any merit, as Lord Burrows stated in the case: "Mr Tinkler and his advisors had looked at the case at a late stage and taken a technical point, that the notice of enquiry was sent to the wrong address, even though that has not caused any prejudice."

Useful guides on this topic

Closure notices
When does HMRC issue a Closure Notice? Can a taxpayer demand one? Are there appeal rights?

How to appeal an HMRC decision
Disagree with a HMRC decision? How to appeal, what type of decision can you appeal and what are your different options when you disagree with HMRC? What are the key steps in making an appeal?

Closure notice invalid: notice of enquiry not validly served (Court of Appeal decision)
In William Tinkler v HMRC [2019] EWCA 1392 the Court of Appeal ruled that a notice of an enquiry sent to a tax agent was not validly served on a taxpayer; the subsequent closure notice was also invalid.

Notice of enquiry can be validly served via an agent (Upper Tribunal decision)
In William Tinkler v HMRC [2018] UKUT 0073 the Upper Tribunal (UT) decided that a copy of notice of an enquiry under section 9A TMA 1970 sent to a tax agent was validly served on a taxpayer.

External links

Tinkler v HMRC [2021] UKSC 39 

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