HMRC would launch an investigation in to your business. They would devote enough resources to make sure that you and your accountant were sufficiently overwhelmed. Most business owners can&#x27;t afford the time and £&#x27;s it takes to defend such an attack, and will most likely pony up the cash.<p>Ninja edit: Most accountants in the UK offer up an insurance that covers your accountants fees if you are investigated by HMRC. It&#x27;s about £120 per year for the insurance and in my opinion a very sensible form of protection. HMRC don&#x27;t always need a reason to investigate, some &quot;high risk&quot; businesses are selected randomly.