Sole trader as second job pension contributions

Hello, after some advice. I have a full time job but have the opportunity to work evenings and weekends as a sole trader. I’m looking to pay all of my sole trader earnings into a private pension. Can I do this before I account for tax via self assessment? As don’t want to claim tax relief on pension contributions before I complete self assessment.

Hi,
You can see guidance here:
Tax on your private pension contributions
Thank you.

Thank you for your reply, I have already reviewed that guide but I couldn’t seem to find an answer my query.

Hi,
You will need to complete a Self Assessment tax return. In it, you will declare your employment income and self employment gross profit and expenses 
Self Assessment: Employment (SA102)
Self Assessment: self-employment (short) (SA103S)
In the SA100 you declare the gross payment into your pension scheme in box 1 of page TR4 or in the equivalent sections of the online tax return. This will ensure that you recieve all of the tax relief due:
How to complete your tax return for Self Assessment
Thank you.