Untaxed interest - PAYE and self assessment

I recently completed a self-assessment tax return for 2022-23. I worked full time during that tax year and this was my first time completing self-assessment. I contacted HMRC before submitting my return regarding the untaxed interest section as I inherited a large sum of money during 2021 and knew this was going to take me over the £1000 interest threshold. During this conversation, I learnt that some of my untaxed interest figures on file at HMRC were estimates and not actuals, and I was advised to contact each bank to request the actual figures, and include these in my self-assessment tax return which I did. As far as I am aware, I have no way of knowing how much untaxed interest I paid tax on via my tax code during the 2022-23 tax year, so included the full figure. I then submitted the tax return and paid the bill. When doing this, I assume I paid tax on the full amount of untaxed interest that I submitted. Is this correct? Would I have already paid tax on at least some of this untaxed interest through my tax code during that year and if so, would I be due a refund? I just phoned HMRC and spoke to someone who at first said he thought I needed to amend the untaxed interest figure by deducting the amount they had on file for that year, and then said the system works it out automatically when submitting the self assessment and that I would not be due a refund. However, he did not sound very certain and I want to be sure.

Hi takula,
If you have had a figure for untaxed bank interest in your tax code, your tax-free allowances will have been reduced by that amount, and you will have paid a corresponding amount of extra tax.
When you then come to submit your Self Assessment return, include the amount of untaxed interest received for the year.
If the amount you include is the same as the amount that was present in your tax code, you will pay no additional tax on your untaxed interest, as any tax due will have been paid through your code.
If the amount is different, you will either be charged the difference or receive the difference back, depending on whether the amount you entered is higher or lower than the amount present in your code.
Thank you.