Leaving date

Hi

I'm hoping someone can help with this query. I'm being made redundant on 31st March 2020 and have been told that I will receive my redundancy payment and PILON on 10th April 2020. The contract I have signed clearly states my last day as 31st March.

I'm aware that PILON is fully taxable whilst the first £30K of the redundancy payment is tax free. My question is that with my leaving date being in 19/20 tax year but my payment being in 20/21 tax year, in which year will tax on the PILON be taxed? I am on PAYE but also do self assessment due to being a higher rate tax payer who claims child benefit.

Any advice would be appreciated as don't want to be hit with an unexpected tax bill at some point.

Thanks in advance :-)