The new rules dictate that, from 2024/25, all unincorporated businesses will be taxed on the profits generated between the start and end of the tax year, from 6 April to 5 April.
This will apply regardless of the year-end that the business prepares its accounts to, meaning that you may need to apportion the taxable profits from two accounting periods.
2023/24 will be the traditional year and there are various tax consequences.
The decision you have to make is whether to change your accounting period to coincide with the tax year (either 31 March of 5 April). If you are going to do it, then change to 31 March 2024 or 5 April 2024, because there are tax beneficial measures to make the transition easier.