Your company taxes sorted for a one-off, fixed price.

Easy, affordable and 100% online.  Learn more

Your company taxes sorted for a one-off, fixed price.

What is a CRN number?

  • 4 min read
  • Last updated 8 Apr 2025

If you’re running a business in the UK, there’s one number you need to have on hand, your CRN number. This unique identifier is key for all kinds of legal and admin tasks and it plays a vital role in keeping your business running smoothly. ✍️

What is a company registration number (CRN)?

Your company registration number is the unique ID your company gets when it’s officially registered.  It’s issued by Companies House and acts like a fingerprint for your business (one of a kind and essential). 

You’ll see it pop up in all sorts of places, whether you’re filing taxes, signing contracts or opening a business bank account. Since its public info, anyone can look it up on the Companies House website. It’s how your company is tracked in official records, so make sure you know it and keep it handy. 🙋

Who needs a company registration number?

If your business is a limited company or an LLP (Limited Liability Partnership) in the UK, you’ll be assigned a CRN number as soon as you register with Companies House. 

But what if you’re a sole trader? In that case, you won’t have one because sole traders and unregistered businesses don’t need to register with Companies House. Instead, they operate under their personal details and Unique Taxpayer Reference (UTR) issued by HMRC. 📑

Where can I find my company registration number?

Need to track down your CRN number? You’ll find it in a few key places:

Official sources

The easiest way to find your CRN number is through official documents, like:

  • Incorporation certificate from Companies House: this document is issued when your company is first incorporated. Keep it safe! 🔐
  • Companies House website: you can also look up your CRN number by visiting Companies House’s official online services.

Other business documents

Your CRN number also appears on various business-related documents, such as:

  • Contracts and legal agreements: if your company has signed contracts, chances are it’s listed there. 
  • Invoices and official correspondence: some businesses include their CRN number on invoices and letters to keep things professional. 📨

Wherever you store it, make sure it’s easy to find, you’ll need it more often than you think! 

Need help with your business taxes? 

Our tax advice service is here to guide you, whether you’re getting started or need support with tax-related questions.

Why do I need a company registration number?

Your CRN number is essential for meeting various legal and tax obligations. You’ll need it for:

  • Getting in touch with Companies House: if you need to make any official changes to your company, like updating your business address or changing directors, your CRN number is required. 
  • Filing tax returns and accounts: it’s necessary to submit accurate financial information to HMRC and your CRN number is a part of that process.
  • Registering for VAT and Corporation Tax: if your company qualifies for VAT or needs to register for Corporation Tax, your CRN number will be necessary to get you set up.
  • Making changes to your company details: whether you’re updating your business name or changing registered office addresses, your CRN number plays a key role in making those updates official. 

In short, your company registration number critical for staying on the right side of the law and making sure your business runs smoothly. So, don’t forget it! ✅

When to display your company registration number

Your company registration number must be displayed on certain business materials and documents, including:

  • Letterheads: whether for internal or external communication.
  • Order Forms: if you provide goods or services through order forms.
  • Emails and Invoices: include your CRN number in the footer of your business emails and on invoices. 📧
  • Compliments Slips: whether handing them out at meetings or sending them with your products.
  • Faxes: yes, even faxes! Your CRN number should be included on any fax cover sheets or business communications. 📠
  • Advertisements: online or in print. 
  • Leaflets, Flyers, and Catalogues: any promotional or informational materials need to include your CRN number for legal transparency.
  • Websites and Online Material: your CRN number must be visible on your business’s website and other online content.

This requirement applies regardless of the format, be it hard copy, electronic or digital. 

Ensuring your company registration number is visible on the necessary materials is crucial for legal compliance and helps establish your company’s legitimacy. So keep it front and centre to stay in the clear! 🔍

Format of a company registration number

Your company registration number typically follows a standard format, but there are a couple of variations depending on where your company is registered:

  • Eight digits for most companies: this is the most common format and applies to companies across the UK. 🔢
  • Two letters followed by six digits for companies registered in Scotland, Northern Ireland or Wales: these companies follow a slightly different format, with two letters at the start to indicate the region, followed by six digits.

Knowing the format of your CRN number is essential, especially when dealing with official records or filing documents. It ensures that everything is correctly identified and linked to your business. 🔗

Let’s recap!

Your company registration number is a must-have for smooth business operations. It keeps you compliant with UK regulations and makes life easier when you’re filing taxes, signing contracts, or handling any other admin tasks. 

You’ll find your CRN number on official docs from Companies House or other business paperwork, so keep it handy!

TaxScouts Newsletter

Want regular tips from us?

Sign up for important updates, deadline reminders and basic tax hacks sent straight to your inbox.

"*" indicates required fields

Category
This field is for validation purposes and should be left unchanged.