Despite HMRC’s pledge to reduce posts, it’s preparing to send around 1.4 million ‘simple assessment’ letters this year. These are aimed at individuals who owe tax but aren’t covered by PAYE or self-assessment, including pensioners, side hustle earners, and those with untaxed income.

Simple assessments are not new. HMRC sends them each year to people it believes may owe tax on income above their personal allowance. This could include savings interest, dividends, rental income, online sales, or pensions. In some cases, people may have wrongly received tax-free allowances.

Each letter will include a detailed calculation of the tax owed and instructions on how to pay. The deadline to settle the bill is 31 January 2026, giving recipients time to check their records and prepare.

HMRC encourages anyone who receives a letter to review the figures carefully. If you think there’s a mistake, you must raise it within 60 days via the gov.uk website. If HMRC agrees with your correction, they’ll issue a revised letter. If they disagree, you can appeal – but only within 30 days of the decision.

Although HMRC is cutting back on physical letters to save an estimated £50 million by 2028/29, these assessment letters will continue. Only those registered with the HMRC app may be contacted by text or email; everyone else will receive letters by post. Earlier this year, HMRC stopped sending six types of ‘non-essential’ corporation tax letters as part of its ongoing cost-saving efforts.

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