Why do hmrc send letters

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Last updated: April 8, 2026

Quick Answer: HMRC sends letters primarily to communicate tax obligations, request information, or notify taxpayers of changes. In 2022-23, HMRC sent over 30 million letters to individuals and businesses, including 12 million related to Self Assessment tax returns. Common reasons include tax calculations, payment reminders, and compliance checks, with specific deadlines like the January 31st Self Assessment payment date. Letters may also address discrepancies in tax records or new legislation, such as updates from the Finance Act 2023.

Key Facts

HMRC sent over 30 million letters in the 2022-23 tax year
12 million letters were related to Self Assessment tax returns in 2022-23
Self Assessment tax payments are due by January 31st each year
HMRC conducts around 250,000 compliance checks annually via letters
The Finance Act 2023 introduced changes affecting tax letters

Overview

HM Revenue and Customs (HMRC) is the UK's tax authority, established in 2005 through the merger of Inland Revenue and Customs and Excise. HMRC sends letters as part of its statutory duty to administer the tax system, collecting approximately £814 billion in taxes in 2022-23. Historically, paper correspondence has been the primary communication method since the 19th century, though digital channels are increasing. Letters serve multiple purposes: notifying taxpayers of liabilities, requesting information under powers granted by the Finance Act 2008, and ensuring compliance with legislation like the Income Tax Act 2007. Specific triggers include annual tax returns, PAYE reconciliations, and investigations into discrepancies. HMRC's letter volume reflects its role in managing 45 million individual taxpayers and 5.6 million businesses, with correspondence often tied to key dates like the tax year end on April 5th.

How It Works

HMRC's letter-sending process involves automated systems and manual reviews. When a tax return is filed or data is received from employers via Real Time Information (RTI), HMRC's systems calculate tax due and generate letters using templates for common scenarios like P800 tax calculations or SA302 statements. For compliance, letters initiate checks under Code of Practice 9 for serious fraud or routine enquiries for errors. The process includes validation against the National Insurance and PAYE Service (NPS) database, with letters typically mailed within 14 days of assessment. Recipients might receive forms like the SA250 for new Self Assessment registrations or reminders for VAT payments due quarterly. HMRC uses risk-based targeting, with letters often requesting documents within 30 days, and follows up with penalties if unanswered, as per the Finance Act 2009 schedule 55 for late returns.

Why It Matters

HMRC letters are crucial for tax compliance and revenue collection, impacting individuals and the economy. They ensure accurate tax payments, preventing underpayments that could cost the UK billions annually; for example, the tax gap was £36 billion in 2021-22. Letters help taxpayers understand obligations, reducing errors and avoiding penalties, which can be up to 100% of tax due for deliberate evasion. In real-world terms, timely responses to letters can prevent interest charges, currently at 7.75% as of 2024. For businesses, letters facilitate VAT and Corporation Tax processes, supporting economic stability. The shift to digital, like the Making Tax Digital initiative, aims to reduce letter volume by 2025, but paper remains vital for accessibility, especially for vulnerable groups.