What is the IN01 form? UK Incorporation Rules for 2026/27

For practitioners handling corporate incorporations in the 2026/27 financial year, the company registration process has undergone its most rigorous overhaul in decades. When clients ask what is the IN01 form, you must advise them that it is the statutory application form required to register a private or public company in the UK.

Historically a straightforward administrative document, the implementation of the Economic Crime and Corporate Transparency Act 2023 (ECCTA 2023) and the February 2026 Companies House fee updates have transformed the IN01 into a strict compliance gateway. This guide details the mandatory contents, new verification procedures, and the updated costs associated with the form.

The Legal Function of the IN01 Form

The IN01 form serves as the formal application to Companies House to bring a company into legal existence. It captures the foundational details of the proposed entity, including its proposed name, registered office address, statement of capital, and details of its initial directors and Persons with Significant Control (PSCs).

Upon successful submission and processing of the IN01 form, the registrar issues a certificate of incorporation.  Under section 15(4) of the Companies Act 2006 (CA 2006), this certificate acts as conclusive evidence that the founders have met all registration requirements and that the company is duly registered under the Act.

The 2026/27 Context: ECCTA 2023 Overhauls

If you are filing an IN01 form in the 2026/27 tax year, you must navigate two major statutory additions introduced by ECCTA 2023. You can no longer rely on older versions of the form.

1. The Statement of Lawful Purpose

The updated IN01 form now mandates a strict “statement of lawful purpose”.  The subscribers (the initial shareholders or guarantors forming the company) must formally confirm that they are forming the company for a lawful purpose and that the company’s intended future activities will be lawful.

2. Identity Verification

The era of registering unverified directors is over. Section 1110B of the CA 2006, introduced via ECCTA 2023, established mandatory identity verification procedures.  The Secretary of State now dictates the procedure and evidence required to verify or reverify an individual’s identity.

When you submit the IN01 form, you must confirm that all proposed directors have completed this statutory identity verification. The verification must occur either directly via the registrar’s digital systems or through an Authorised Corporate Service Provider (ACSP) before Companies House will accept the incorporation.

Digital vs. Paper Submissions and 2026 Fees

Section 1063 of the CA 2006 grants the Secretary of State the power to set the fees payable to the registrar for processing documents like the IN01 form.

On 1 February 2026, Companies House significantly increased the fees associated with company registration. The method you choose to submit the IN01 directly dictates the cost and the processing timeline:

• Digital/Software Submission: Companies House actively encourages practitioners to submit the IN01 digitally via approved software or the GOV.UK portal. The standard digital incorporation fee is now £100.  If you require an expedited, same-day incorporation using software, the premium fee is £156.
• Paper Submission: If you choose to submit a physical, paper IN01 form, the statutory fee increases to £124. Furthermore, paper submissions take substantially longer to process, often delaying the client’s ability to open a corporate bank account or register for taxes.

Summary Table: IN01 Form Requirements 2026/27

For completeness, before drafting the IN01 application, practitioners must ensure all proposed directors possess valid, government-issued photo identification to clear the new ECCTA 2023 verification hurdles without delaying the incorporation timeline.