{"id":611,"date":"2026-04-03T13:50:56","date_gmt":"2026-04-03T13:50:56","guid":{"rendered":"https:\/\/www.taxpartnersuk.com\/blog\/?p=611"},"modified":"2026-04-12T19:26:22","modified_gmt":"2026-04-12T19:26:22","slug":"ignorance-of-tax-law-is-bliss-the-reasonable-excuse-debate","status":"publish","type":"post","link":"https:\/\/www.taxpartnersuk.com\/blog\/ignorance-of-tax-law-is-bliss-the-reasonable-excuse-debate\/","title":{"rendered":"Ignorance of tax law is bliss \u2013 the reasonable excuse debate"},"content":{"rendered":"

For many years, it has been impressed upon tax advisers that the Latin legal maxim Ignorantia juris non excusat<\/em> (ignorance of the law is no excuse) provided no defence in tax cases. Historically, a failure to keep abreast of statutory tax obligations has provided no safeguard against penalties. However, the landscape surrounding UK tax compliance has somewhat shifted in recent times.<\/p>\n

Consider the position of UK tax resident individuals who are required by law to pay UK tax on their worldwide income and gains. Those in employment will generally be content in the knowledge that their employer has fulfilled all their tax obligations by deducting a portion of their salary and remitting it to HMRC and job done. Blissfully ignorant of the intricacies and complexities of the UK tax law, they may often overlook a piddly sum of bank interest sitting in an overseas bank account, thereby failing to notify HMRC that they have income outside employment. Such oversight can then give rise to what\u2019s referred to as \u2018failure to notify\u2019 penalty.<\/p>\n

The UK operates a \u2018self-assessment\u2019 system, under which taxpayers themselves are required to determine independently whether they owe any tax to HMRC. Individuals who are not already within the self-assessment \u00a0system are nevertheless required to assess their own position and notify HMRC (s.7, Taxes Management Act 1970 (TMA) no later than 5 October following the end of the relevant tax year, should they believe that tax is owing. Upon notification, HMRC will usually issue a notice requiring the taxpayer to file a tax return (s.8, TMA 1970<\/a>). Failure to tell HMRC (notify chargeability under s.7 TMA) attracts penalties, which are governed by Schedule 41, Finance Act 2008. These penalties are geared to the amount of tax at stake, ranging from 0% to 100% and depend on various factors, such as whether notification was made voluntarily or after a prompt from HMRC, whether the delay in notification exceeded twelve months, whether the taxpayer\u2019s conduct was deliberate or non-deliberate, and whether there was any \u2018reasonable excuse\u2019 for the failure.<\/p>\n

What constitutes a \u2018reasonable excuse\u2019 (Para 20, Schedule 41, FA 2008<\/a>) is not defined in legislation. In cases where the conduct was non-deliberate, penalties may be set aside if the taxpayer can satisfy HMRC or the tribunal on appeal that there was a reasonable excuse for the act or omission.<\/p>\n

This raises the question: could ignorance of the complexities of UK tax law constitute a reasonable excuse for failing to notify chargeability, thereby avoiding penalties? Recent First-tier Tribunal (FTT) cases demonstrate that ignorance of tax law can, in certain circumstances, amount to a ‘reasonable excuse’.<\/p>\n

This article examines the development of tribunal decisions, contrasting harsh historical rulings with the more nuanced modern approach that favours taxpayers who have, genuinely and reasonably, fallen foul of obscure tax provisions.<\/p>\n

For years, the FTT was split, producing conflicting ‘Yes’ and ‘No’ judgments regarding whether unawareness of tax obligations constituted a valid defence. For example:<\/p>\n