self assessment commercial software

Hi I would like to file tax return by self assessment commercial software. However, when I wanted to submit information online it showed that the Self Assessment service is not activated for my account on HMRC's website. Actually I can sign in using Government gateway and see my account, may I ask how to activate for my account? How can I get the activation code? Thank you for your help

Hi F_Keung,

You will need to enroll for Self-Assessment online first.
Please go to Sign in using Government Gateway, select 'Government Gateway' to log in with their User ID and Password and select `enrol for service’ at the side of Self Assessment on the "Services You can add" page

Thank you.