When Ignorance of the Law Actually Works: What the Julian (2026) Case Revealed
What to do if HMRC issues a penalty
When HMRC hits you with a penalty for a tax breach—whether it’s a late filing, an error, or a delayed registration—taxpayers have one primary line of defense: proving they had a “reasonable excuse.” In practice, this is the most common argument used when appealing HMRC fines. First, HMRC evaluates the situation and makes a decision. If they reject your explanation, you can take the dispute to a Tribunal. Therefore, the question of a reasonable excuse is tackled in two stages: first by the tax authority, and then by the court.
What is a reasonable excuse?
The law doesn’t actually provide a strict definition for this term. However, based on case law (such as The Clean Car Company Ltd [1991]), an objective test applies: the taxpayer must have acted as a reasonable person would have, exercising due diligence.
This means it’s not about what you thought, but rather how objectively reasonable your actions were. The court will take your circumstances into account, including your experience, knowledge, and the scale of your business.
The Julian (2026) Case: When ignorance actually worked
According to an analysis by Croner Tax Weekly based on the First-tier Tribunal’s decision in Julian (2026), the court examined the situation of farmers using the Agricultural Flat Rate Scheme.
Following a legislative change in 2021, they were required to register for VAT. However, neither the farmers nor their accountant noticed the rule change, resulting in a penalty for failure to notify.
Normally, ignorance of the law isn’t a valid excuse. Yet, the Tribunal took into account that the change was highly technical, poorly publicized, and definitely not obvious to a layperson. Furthermore, the accountant did not specialize in VAT. The court concluded that, under these specific conditions, the taxpayers could not have reasonably discovered the change. As a result, their ignorance was accepted as a reasonable excuse.
When ignorance of the law can be a reasonable excuse
Case law shows that this argument rarely succeeds, but it is possible if:
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The legislation is complex or was recently changed.
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The changes weren’t clearly communicated to taxpayers.
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Reasonable attempts were made to comply with the rules.
Conversely, ignorance will be rejected if the obligation is common knowledge, the information is easily accessible, or the taxpayer simply made no effort at all.
The Accountant’s Responsibility: Where to draw the line
An accountant’s mistake can be considered a reasonable excuse provided you hired a qualified specialist, gave them complete information, and the error wasn’t glaringly obvious.
However, this defense falls apart if the accountant is clearly incompetent, the taxpayer exercised zero oversight, or the mistake could have been caught with a basic check. The courts evaluate the behavior of the taxpayer, not just the actions of the accountant.
Excuses HMRC usually accepts
Circumstances that may qualify as a reasonable excuse include:
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Serious illness.
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Technical failures beyond your control.
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Mistakes made by a qualified advisor.
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Highly complex legislative changes.
Excuses HMRC usually rejects
As a general rule, HMRC will not accept:
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Forgetfulness or being “too busy.”
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Poor record-keeping.
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Ignoring official notices.
The Crucial Condition: No Unreasonable Delay
Even if you have a rock-solid reasonable excuse, you are legally required to fix the breach immediately. For example, once you recover from an illness, you must file your return; once you spot an error, you must correct it right away. Dragging your feet can completely invalidate your defense.
Conclusion
The Julian (2026) case doesn’t rewrite the general rule, but it does clarify how it’s applied. Ignorance of the law still rarely saves the day. However, in situations where an obligation couldn’t reasonably be discovered even with due diligence, this defense remains a viable option.
Sources:
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Croner Tax Weekly — Analysis of the First-tier Tribunal decision in Julian (2026)
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HMRC Guidance — Reasonable excuse and penalties
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The Clean Car Company Ltd [1991] BVC 568
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Perrin v HMRC [2018] UKUT

