HMRC is sending a second wave of Simple Assessment tax letters to some UK households from October, and officials are urging people to read them carefully to avoid paying twice. Around 1.8 million Simple Assessments are expected to be issued this year, but some people will receive a further letter relating to Bank and Building Society Interest (BBSI) data.
Why a second letter may arrive
HMRC explains that a Simple Assessment may be issued if Income Tax cannot be collected through a tax code. This could apply if you owe £3,000 or more in tax, need to pay tax on your State Pension, or have untaxed income such as savings interest or dividends.
According to HMRC, some savers will be sent a second tax demand from next month that includes tax owed on savings interest, plus the amount stated in the first letter, even if that tax has already been paid. The latest Simple Assessment will show the total amount of tax owed for the year, including any amounts shown in earlier bills.
How to avoid overpaying
HMRC states that if you have already paid the amount from an earlier bill, you only need to pay the difference between what you have paid and the total in the latest bill. An HMRC spokesman said: “To prevent customers from overpaying, our letters now make clear that customers don't need to pay the total tax shown if they've already made a payment towards a previous simple assessment bill from earlier in the year.”
Joseph Adunse, from accountancy firm Moore Kingston Smith, warned that thousands of taxpayers could be impacted. He said: “HMRC are creating more work for people, and potentially causing overpayments – these people won't get automatic refunds.”
What to do if you receive a letter
HMRC’s website notes that more than one Simple Assessment bill for a tax year can be sent if new or revised information is received after the first bill. The first letters began reaching working-age customers from 30 June 2026, with pensioners receiving them from 12 August 2026. The second tranche will be sent between October and December 2026.
HMRC advises people to deduct any tax already settled from the second figure to calculate the amount actually owed. If you have overpaid, you will need to contact HMRC to claim a refund. Payments can be made via the HMRC app, online through GOV.UK, by bank transfer or by cheque. Full guidance on Simple Assessment is available on GOV.UK.
