Thousands of savers could accidentally pay HMRC twice when a new round of tax bills arrives from next month.
The letters will add tax owed on savings interest, but may also include amounts people have already paid.
HMRC is sending a second Simple Assessment to some taxpayers after receiving interest figures from banks and building societies.
The new letter shows the total tax due for the year, so anyone who has settled an earlier bill should check what they have paid before sending more money.
It is the second year running that savers have faced this confusion.
Tax advisers fear people who do not have professional help could see the larger figure on the new letter and pay it in full.
The number of people expected to pay tax on savings interest has more than tripled, rising from 1.22 million in 2022-23 to an estimated 4.51 million in 2026-27.
HMRC expects to issue around 1.8 million Simple Assessment letters for the 2025-26 tax year, although it has not said how many recipients will get a second one.
Joseph Adunse, of accountancy firm Moore Kingston Smith, warned that thousands could be caught out and urged anyone receiving another bill to check it carefully.
“HMRC are creating more work for people, and potentially causing overpayments these people won’t get automatic refunds,” Mr Adunse said.
Savers who have already paid one tax bill could overpay
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GETTYHe expressed surprise that the problem had resurfaced, given that the same issue arose last year. “Surely there must be a way for HMRC to see that you’ve already paid?” he added.
Mr Adunse suggested it would be far more efficient for the tax authority to consolidate everything into a single bill, but noted that HMRC’s priority appeared to be collecting revenue as quickly as possible.
HMRC has previously explained that it can only issue simple assessments relating to savings interest once banks have provided the relevant data.
Joe Lytwyn, personal finance expert at thimbl.com, urged savers to take a careful approach before making any further payment.
“Receiving a second tax bill can immediately make people think they owe another large payment, particularly when it comes from HMRC,” Mr Lytwyn said.
It is the second year running that savers have faced this confusion
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GETTY“But the important thing is not to automatically assume that the total shown on a new letter is the amount you still need to pay.”
Mr Lytwyn recommended comparing the latest assessment against the original, checking bank statements for any payment already made, and ensuring the outstanding balance is clearly understood.
“Keeping copies of previous HMRC letters and confirmation of any payments you’ve made could make this considerably easier,” he added.
For those who remain uncertain, Mr Lytwyn advised contacting HMRC directly for clarification, noting that two letters containing overlapping figures could easily confuse anyone who does not regularly deal with tax assessments.
The growing number of affected savers reflects broader pressures on household finances
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GETTYThe growing number of affected savers reflects broader pressures on household finances. Frozen tax thresholds combined with rising state pensions are dragging more people into the tax net.
The state pension is set to exceed £13,000 from April 2027, surpassing the £12,570 personal allowance, though the Government has pledged that retirees relying solely on the state pension will be exempt from income tax.
Up to £5,000 in savings interest can be earned tax-free, but this allowance is reduced pound for pound by any other income above the personal allowance.
Basic-rate taxpayers also benefit from a £1,000 personal savings allowance, which drops to £500 for higher-rate taxpayers and disappears entirely for those on the additional rate.
A spokesman for HMRC 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.”

