How is total income calculated over a financial year - personal savings allowance?

Good morning I used to be a basic rate tax payer but recently moved to the higher rate category. As I have fixed bond savings which will accrue interest this financial year 24/25, I would like to find out whether my personal savings allowance will stay as £1000 or decrease to £500. Does the HMRC calculate one's income combining the salaries through the year and then establishing whether the total is above or under £50,270? If positive, will any interest exceeding the personal savings allowance of £1000 be taxed at 20% or 40%? Finally, how can any tax due be paid, except for adjusting one's tax code? My situation will be different in the next financial year 25/26. The information available on https://www.gov.uk/apply-tax-free-interest-on-savings and https://www.gov.uk/income-tax-rates does not answer these questions. Thank you in advance. S

Hi ,
 

If you are a higher rate (40%) taxpayer in the current tax year the personal savings allowance will decrease to £500. We will base your earnings for the year on a estimate, you can ensure the estimate we hold is correct by logging into the personal tax account and updating this where necessary. We aim to collect the correct amount of tax during the tax year based on estimated employment and savings income however if this is not possible we will issue a tax calculation at the end of the tax year which will detail how any underpayment will be collected if appropriate. See :   Personal tax account: sign in or set up  .     Thank you .