I opened a Nationwide Building Society account in November 2024 with some inheritance money, and closed it in May 2025, earning about £1,500 in gross interest. As my personal savings allowance is £1,000, I contacted HMRC and was told to expect a tax bill for the excess (around £100), or to follow up if nothing arrived, as notifications can sometimes be delayed. I have tried calling HMRC several times but get cut off after about 20 minutes on hold. I would prefer to pay this as a one-off bill rather than via a tax code adjustment, especially as I am expecting a larger amount of savings interest this year. What’s the best way to handle this? 

Arthur Weller replies: 

Interest counts as income for tax purposes according to the date when it is credited to the recipient's account. It is not apportioned over the period when it accrues. If the interest was only credited to your account when you closed it, then it falls within the 2025/26 tax year. You will only know how much income tax is due on this £1,500 at the end of the 2025/26 tax year (5 April 2026), when you can be certain how much income you received in the year. Perhaps you are best off waiting for 5 April 2026 and then writing to HMRC.