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Form IN01: Register a UK Company (2026 Guide)

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Part ofCompanies House Forms UK

Written by Brad Askew Solicitor (non-practising)
Brad is on the roll of solicitors of England & Wales but does not hold a practising certificate and does not provide legal advice.
Updated June 2026 · England & Wales
Setting up a limited company in the UK is something thousands of people do every year, but the paperwork behind it catches plenty of first-time founders off guard. Form IN01 is the application Companies House uses to register both private and public companies, and it pulls together a lot of decisions you'll need to make upfront: who the directors are, where the registered office sits, how shares are issued, and what the company's constitution looks like. Getting these right at the start saves hassle later, because amending them after incorporation means more filings, more fees, and sometimes more awkward conversations with co-founders. This page walks through what IN01 covers, what you'll need to have ready, and the sort of pitfalls I've seen trip people up when they try to do it in a rush.

What this document is

Form IN01 is the official application form for incorporating a new company in England, Wales, Scotland, or Northern Ireland. It's lodged with Companies House, the executive agency responsible for maintaining the UK's register of companies, and it captures every piece of information needed to bring a company into legal existence.

That includes the proposed name, the type of company (private limited, public limited, unlimited, or limited by guarantee), the registered office address, the details of the initial directors and any company secretary, the people with significant control (PSCs), and, for companies with share capital, a statement of capital setting out the shares being issued and their rights. You'll also need to confirm the company's Articles of Association, which are the internal rulebook governing how the company is run.

Most small companies use the Model Articles published by the Secretary of State, but you can adopt bespoke Articles or amend the Model Articles to suit your situation. Once IN01 is accepted and the fee paid, Companies House issues a Certificate of Incorporation and the company legally exists from that date.

How to use this document

  1. Pick a name that will actually get through. Companies House rejects names that are identical or too similar to ones already on the register, and there's a separate list of 'sensitive' words (like 'bank', 'royal', or 'chartered') that need permission before you can use them. Search the Companies House register before you commit to branding, stationery, or a domain.
  2. Decide your company structure and shareholdings. Before you fill in IN01, work out whether you want a private company limited by shares, limited by guarantee, or a public limited company, and agree the split of shares between founders. The statement of capital locks in the number of shares, their nominal value, and what rights attach to them, so it pays to think this through properly.
  3. Sort your registered office and director details. You'll need a UK registered office address (which becomes public on the register) and full details for every director: name, date of birth, nationality, occupation, service address, and usual residential address. The residential address is protected from public view but still has to be provided to Companies House.
  4. Choose your Articles of Association. You can adopt the Model Articles wholesale, adopt them with amendments, or file entirely bespoke Articles. For most straightforward small companies the Model Articles are fine, but if you have multiple shareholder classes, unusual voting arrangements, or investor requirements, bespoke Articles are usually worth the effort.
  5. Submit IN01 and pay the fee. You can file online through Companies House's web service (which is faster and cheaper) or on paper. Online applications are typically processed within 24 hours, while paper filings take longer. Once accepted, you'll receive the Certificate of Incorporation with your company number, and the company is officially born.

Common questions

If you're dealing with this kind of situation, speak to an experienced legal adviser who can walk you through it — from £149.

Common questions

Q What's the difference between a private and a public company?
A private limited company (Ltd) cannot offer shares to the general public and is the default choice for most UK businesses. A public limited company (PLC) can offer shares publicly and list on a stock exchange, but it faces stricter rules on minimum share capital, accounting, and governance. Most startups and small businesses incorporate as private limited companies and only re-register as PLCs later if they genuinely need public investment.
Q Can I use my home address as the registered office?
Yes, you can, but bear in mind the registered office address appears on the public Companies House register, so anyone can look it up. Many directors prefer to use an accountant's address, a registered office service, or a separate business address to keep their home out of public view. The address must be a real, physical UK address where documents can be served, not just a PO box.
Q Do I need a company secretary?
Private limited companies are not required to appoint a company secretary, though you can choose to have one. Public limited companies must appoint a company secretary who meets certain qualification requirements set out in the Companies Act 2006. If you're setting up a small private company, skipping the secretary role is perfectly normal.
Q What is a person with significant control (PSC)?
A PSC is an individual who ultimately owns or controls the company, typically someone holding more than 25% of the shares or voting rights, or who otherwise has significant influence. You must identify and record PSCs on IN01 when you incorporate, and keep the register updated afterwards. This is part of the UK's transparency rules aimed at preventing misuse of corporate structures.
Q How long does incorporation take?
Online applications filed through the Companies House web service are usually processed within 24 hours, often much quicker. Paper applications take considerably longer, typically eight to ten working days. If Companies House spots a problem with your application, for example a name clash or missing information, it will be rejected and you'll need to resubmit, which obviously adds delay.
Q Can I change my company details after incorporation?
Yes. You can change the registered office, appoint or remove directors, amend the Articles, issue new shares, and change the company name after incorporation, but each change requires its own filing with Companies House (and sometimes a shareholder resolution). Getting things right on IN01 at the start saves time and filing fees later, particularly for things like share structures where mistakes are awkward to unwind.
Q What happens after I receive the Certificate of Incorporation?
The certificate confirms the company legally exists. You'll then need to register for Corporation Tax with HMRC within three months of starting to trade, set up a business bank account, and make sure you're on top of ongoing obligations like the annual confirmation statement and statutory accounts. If you'll be taking on staff or crossing the VAT threshold, further registrations will apply.
If you're dealing with this kind of situation, speak to an experienced legal adviser who can walk you through it — from £149.

Sources

This guide is based on primary UK law and official guidance.

Brad Askew, Solicitor (non-practising)

Written & reviewed by

Brad Askew Solicitor (non-practising)

Brad is on the roll of solicitors of England & Wales but does not hold a practising certificate and does not provide legal advice. LegalDocuments.co.uk is not a law firm and does not provide regulated legal advice.

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Legal disclaimer
This article is for general information only. It is a tool to help you find your way — not legal advice, and not a substitute for speaking to a qualified adviser about your situation.