TaxPensionConfusion

Hello, I have earned £150,500 this year 24-25. I'd like to make contribution to my pension to bring me under the £100k threshold where your personal allowance begins to taper. The amount I'd like to pay into my pension is £50,505 to take me under that threshold. So, do I need to pay that full amount into my pension myself (£50,505) or do I pay £50,505 minus 20% as that 20% is collected from the government by my pension provider and that counts as part of the total to bring me under the £100k threshold? Many thanks!