Tax refund of backpay

Hi, I received my March 2024 income in April 2024 (2023/24 income free from tax and need to pay tax in 2024/25), and paid extra tax due to the backpay. Receiving 2 months of income in April also makes my income estimate for the fiscal year 2024/25 much higher which means I will need to pay more taxes in the following months. How I can claim a tax refund for the backpay? After claiming the tax overpayment, will my monthly tax payment be adjusted to the normal level? Thanks!

Hi xxx,
The payment is taxed when paid to you.
If the payment was received after 5 April 2024 then will be taxed in the 2024/25 tax year. 
Thank you.