Higher income child benefit repayment

Trying to adjust my income to account for Pension contributions that I have not received tax relief for - do I adjust the total income before tax on my self assessment, if not where do I input this adjustment

Hi,
On the tailor your tax return section online you would answer yes to the question - Did you make contributions towards a personal pension or retirement annuity? This will open the section to declare the pension contribution made to receive the tax relief.
Thank you