[header] How to register a uk company [title] Register your income tax and national insurance details with hm revenue and customs. [step] You can register online on their website, by phone using their helpline or by mail by completing a cwf1 form and mailing it to hm revenue and customs. [title] Know your national insurance number or receive one by contacting jobcentre plus, you will need one to register your company and set up your income tax. 
[title] Notify hm revenue and customs when you begin working as a sole trader. [step] You cannot register at an earlier time.