How to register for tax self-assessment to get full contributions to my SIPP

Hi, I am a 40% tax-payer with a SIPP, currently getting the standard 20% contribution added to any payments I make into my SIPP. I undertstand that in order to get the full allowable government contributions to my SIPP for the year, I must register for self-assessment by early October. However, when logging into my Gov.UK account and attempting to register for self-assessment, in the list of, 'Why do you need to complete a tax return?' I cannot see a tick-box that applies to me. For example, 'I receive annual income from a trust or settlement' or 'I've untaxed income which cannot be coded in PAYE' don't seem relevant to my specific need to apply for self-assessment. There's no reference to SIPP contributions. Am I looking in the right place to register for self-assessment, and if I am, which tick-box do I want to tick? Thanks for any help.

Hi yingyang99,
You do not need to file a Self Assessment return to claim tax relief on your Personal Pension Payments.
You can do this by phone, webchat or post here:
Income Tax: general enquiries .
You can read more here:
Tax on your private pension contributions
Thank you.