You can elect to make voluntary class 2 voluntary contributions if you have added a Self-Employment page and your profit is below the Class 2 NIC limit.
Click on 'SAVE' > 'CONTINUE' > 'YES'
Answer 'Yes' to the question 'Do you want to voluntarily contribute towards Class 2 Contribution?'
Tick the box to pay the maximum amount (£163.80 - 2023/24)
or enter the voluntary contribution you need to make (max £163.80)
Click on 'SAVE' at the bottom of the page.