Core Points - Many UK companies may suddenly receive a Notice of Penalty Determination from HM Revenue & Customs (HMRC) during their initial operations or when changing accounting agents, indicating automatic fines for late submission of Corporation Tax Returns or late payment of corporation tax [1] - Companies are subject to fixed penalties for late submissions and may incur daily penalties and tax-geared penalties if delays continue, as outlined in the Finance Act 2009 [1] Summary of Corporation Tax Filing and Payment - The Corporation Tax Return (CT600) must be submitted within 12 months after the accounting period ends, while corporation tax payment is due 9 months and 1 day after the accounting period ends [3] - Late filing penalties are automatically triggered after the deadline, and late payment penalties are calculated based on the number of days delayed [3] Appeals and Reasonable Excuse - Companies have the right to appeal against penalties within 30 days of the notification date, citing either incorrect penalty determination or reasonable excuses for non-compliance [4] - Reasonable excuses include unforeseen circumstances that prevented compliance, such as the death of a director, sudden illness, system failures, or natural disasters [6] Acceptable and Unacceptable Reasons - Acceptable reasons for appeal include unforeseen events like the death of a director or technical issues with HMRC systems [6] - Unacceptable reasons include insufficient funds, difficulties with HMRC's online system, or negligence [7][8] Preparing for an Appeal - Companies should first identify the reason for the delay and confirm if it falls under the category of reasonable excuses [9] - Evidence must be collected to support the appeal, including medical documents, communication records with accountants or HMRC, and screenshots of system errors [10] - A professional appeal letter should be drafted, detailing the reasonable excuse, its impact on compliance, and requesting the cancellation or reduction of the penalty [11]