HMRC’s Simple Assessment Letters
If you’ve recently had a tax letter land on your doormat, you’re not alone. HMRC is sending out 1.4 million “Simple Assessment” notices this year. These letters are aimed at people who don’t normally complete a tax return, but who HMRC believes still owe tax.
Unfortunately, saying “I didn’t know” won’t get you off the hook. If the assessment isn’t dealt with, HMRC can charge penalties and interest — so it’s important to understand what the letter means and what action you need to take.
In this article, we’ll explain:
What a Simple Assessment is
Who is likely to receive one
Key deadlines you need to know
What to do if you think HMRC has got it wrong
What Is a Simple Assessment?
A Simple Assessment is HMRC’s way of calculating the tax it thinks you owe — without asking you to fill in a full Self Assessment tax return.
The letter includes:
A breakdown of your income and allowances
HMRC’s calculation of unpaid tax
Instructions on how to make payment
The deadline to pay is 31 January 2026, giving plenty of time to prepare — but the letter mustn’t be ignored.
Who Might Receive One?
You may receive a Simple Assessment if you have:
Pension income above your personal allowance
Interest from savings or dividends that hasn’t been taxed
Rental income or earnings from a side hustle
Received tax-free allowances that HMRC believes you weren’t entitled to
In other words, even if you’ve never filed a tax return before, HMRC may still expect you to pay tax on certain types of income. This is possible because HMRC now receives data directly from banks, pension providers, letting agents, and online platforms.
What If You Disagree?
If you believe the calculation is wrong, you must act quickly.
You have 60 days from the date of the letter to tell HMRC you disagree
If HMRC accepts your correction, they’ll issue a new letter
If they don’t agree, you have 30 days to lodge a formal appeal
Failing to act within these time limits means the tax charge will stand.
Why This Matters
Many people who receive these letters are not used to dealing with HMRC directly. Pensioners, landlords, or those with small side incomes often assume tax is automatically taken care of — and are caught off guard when a letter arrives.
The key message is simple: don’t ignore the letter. Check the figures against your own records and take action quickly if something doesn’t look right.
Need Help?
At Tax Matters, we help individuals make sense of HMRC assessments and deal with any issues that arise. Whether it’s checking the numbers, correcting errors, or handling correspondence with HMRC, our team can guide you through the process.
