Do we calculate tax on adjusted net income?

Hi, I posted a question the other day, to simplify I need to ask if we calculate tax on the adjusted net income? For example if A has earned £160,000 trading profit in 2023/24 and has paid £6400 to charity under the gift-aid scheme. Then his reduces the ANI to £152,000, since we reduce the income by the gross gift-aid, in this case, 6400×100/80 =8,000. What I need to know is if we carry out our tax computation on the £152,000 or the £160,000. I am stuck here since the lecture states our total income is £160,000 and that is our taxable income, however, I’m under the impression we calculate tax on the ANI.