Hi
When HMRC receives your untaxed interest details for the 2023/24 tax year from the bank and building societies we would then review your record.
Any underpayment of tax would be then collected in the 2025/26 tax code. Your 2024/25 tax code would be updated to include the savings income from 2023/24 as an estimate.
If your savings income has changed you can contact HMRC with the estimated details and we would amend your tax code.
If you do not want to have the underpayment collected in your tax code then you can make a payment using your personal tax account instead.
It would be a similar situation regarding your dividend income.
If you do not want the savings income or dividend income included in your tax code then you would need to register for Self Assessment and complete a tax return at the end of each tax year.
You can register at
Register for Self Assessment if you are not self-employed
Thank you