Hi,
If you are a self-employed and are wanting to pay off the previous tax year, you do not pay with an 18 digit reference number, you pay your class 2 National Insurance through Self-Assessment.
Unless you are a part of the Self Employment Exemptions group, in this instance yearly voluntary bills will be issued out to you.
If your earnings are below the Small profits threshold which is currently £6,725 pa, you will not be charged class 2 automatically but you can opt to pay your class 2 voluntary through your self-assessment account.
If your earnings are in between the Small Profit Threshold and the Lower Profit Threshold (£12,570) your class 2 will be treated as made and will be covered for you and you will not need to pay.
If your earnings are over the Lower Profits Threshold you have to pay your class 2.
You will need to contact Self-Assessment via their Webchat or phone line and you can arrange with them the most convenient way for you to pay.
Please find the link below to their contact details.
Self Assessment: general enquiries
If you click the Ask HMRC online, you can speak to them via webchat.
Thank you.
