Tax and National Insurance
Your savings tax letter lands by December. Do not pay it twice.
HMRC's savings interest Simple Assessment letters go out from October to December 2026, and each one restates the whole year's tax, not just the new amount.
31 January Deadline to pay a letter dated before 31 October 2026
HMRC is issuing around 1.8 million Simple Assessment letters for the 2025-26 tax year, and the batch that matters most to savers has not started. It runs from October to December 2026, and because every Simple Assessment restates the whole year’s tax rather than just the new amount, paying it in full on top of a letter you have already paid means paying twice. That autumn batch is the one carrying the interest your bank or building society reported.
Who gets a letter, and when
HMRC sends a Simple Assessment when you owe income tax it could not collect through your tax code and you do not file a tax return. Untaxed income such as savings interest is one reason. Tax due on your State Pension is another, and so is owing £3,000 or more.
| Group | When the letter is sent |
|---|---|
| Working-age customers | From 30 June 2026 |
| Pensioners | From 12 August 2026 |
| Anyone with bank or building society interest added | October to December 2026 |
Why the second letter is not a second bill
The Association of Taxation Technicians flagged this on last year’s round, when the 2024-25 letters went out. “A Simple Assessment always shows the total tax due for the year,” it wrote. “The assessments do not take into account any payments that have been made following earlier letters.”
HMRC gets bank and building society figures late in the cycle, so someone assessed in the summer on a pension can be assessed again in the autumn on that same pension plus the interest.
Take what you have already paid for that same tax year off the figure on the newest letter, and pay the difference. Say the summer letter showed £650 and you paid it, and the autumn letter for the same year shows £900: what is left to pay is £250, not £900. Check the year first — a payment made for 2024-25 does not come off a 2025-26 assessment.
The two dates that matter
If you think any information on the letter is wrong, you must contact HMRC within 60 days of getting it.
A letter dated before 31 October 2026 must be paid by 31 January 2027. A letter dated on or after 31 October 2026 must be paid within three months of its own date. You can pay the whole amount at once or make a series of smaller payments before the deadline, and you do not have to file a tax return.
How much interest is tax free
| Tax band | Interest you can earn tax free |
|---|---|
| Basic rate | £1,000 |
| Higher rate | £500 |
| Additional rate | £0 |
On top of that, up to £5,000 of interest is tax free if your other taxable income is under £17,570. Every £1 of other income above your personal allowance cuts that £5,000 by £1, so it is gone by the time other income reaches £17,570.
Check the interest figure against your own statements before you pay anything. HMRC uses what the banks report, and the letter is the first time most people see a year of it added up.
If you work in the NHS and want to see what PAYE already takes before any of this, our take-home calculator shows it line by line. Where our figures come from is set out in sources.
Where these figures come from
- HMRC urges customers not to ignore Simple Assessment letters — GOV.UK (HM Revenue & Customs)
- Pay your Simple Assessment tax bill — GOV.UK
- Watch out for multiple Simple Assessment letters — Association of Taxation Technicians
- Tax on savings interest: how much is tax free — GOV.UK
- HMRC error leaves savers in 'real danger' of overpaying tax bills — GB News
Every figure traces to a dated document — the line this section is named after. If one here is wrong, tell us and it gets fixed publicly. Work out your own figures.