Companies House Integration

Learn how to import key dates and updates for all of your UK clients with a couple of clicks.

Erin Jamison avatar
Written by Erin Jamison
Updated over a week ago

If your practice is located in the United Kingdom, you can integrate your organisation contacts with Companies House. Learn how importing data from Companies House can save time and simplify processes.


Why use Companies House with Karbon?

Syncing Karbon with Companies House makes all of your client’s key statutory information accessible with just a few clicks.

This allows for:

  • Maintaining Karbon as a source of truth by keeping data up to date

  • Pulling in data when onboarding new clients to help decide when to kick-off compliance work

  • Adding Organisations in Karbon from Companies House by searching for the Company Number or Company Name

  • Linking existing Organisation contacts to their corresponding Companies House record

  • Exporting all your client’s data to quickly build reports or mailing lists

  • Instantly identify which client data has changed since the last update

  • Giving team members who aren’t familiar with a client visibility on key dates during handovers

Connecting Companies House with Karbon

This guide will walk you through the three-step process which takes about five minutes to set up:

  1. Registering with Companies House

  2. Creating an Application to get an API Key

  3. Linking Karbon & Companies House with the API Key

Note: You will need a Company Registration Number saved for all of the contacts that you’d like to sync.

1. Register with Companies House

Registering is how you tell Companies House that you want to access their data with your software, which in this case is Karbon. Once you've registered and told them about your software, you will be provided with an API Key, which can be thought of as a password that your software uses to login to Companies House.

Visit Companies House Developer Hub to register your account.

2. Create your app and API Key

Once registered and logged in, you will need to select Create Application.

You will then be asked to add the details of your application. We recommend calling the application "Karbon" and adding a clear description.

You will also need to select Live as the environment for your application.

You will then see an overview with the Application Details. While on the Application Details screen, select Create new key.

Then add a name for the key, a description and select REST.

Then select Create key, the API Key will be created.

Once saved, you will be taken back to the Application details where you will be able to see the key.

Copy the API key to your clipboard as you will need it for the next step.

3. Linking Karbon & Companies House with the API Key

Now you can add the API key to Karbon and create a secure connection. Start by opening Karbon in a new window and navigate to Connected Apps.

Settings > Connected Apps > Companies House > Manage. Then select Add API Key, which will reveal a pop-up modal.

Paste in the API key and select Update. You should now see a Sync Now button.

Click on it!

Note: You will only have to add your API key initially, as Karbon saves the API key. If you have a lot of data to sync, it may take some time. You can navigate away from the page and the sync will continue in the background.

Once complete, you will see the option to Download in the summary column. After the initial sync, syncing will occur continuously, keeping your synced Organisation data from Companies House up to date and relevant.

If your practice is located in the United Kingdom, integrating an organisation with Companies House will let you import a company’s details to Karbon.

From the organisation's contact page that you want to import details for, go to the details tab.

Scroll to connected applications and select manage connections. There, you have the option to import company details from Companies House.

You will then be able to enter the Companies House Company Registration Number.

Importing details from Companies House adds information to the following contact fields:

  • Legal name

  • Company registration date

  • Financial year-end day and month

  • Company officers

  • Registered office address

  • Dates for last accounts completed

  • Dates for next accounts due

  • Dates for next accounts made up to

  • Dates for next confirmation statement

Using your integration with Companies House

Add Organisations via the Company Number or Company Name

You can easily add Organisations in Karbon from Companies House by searching for the Company Number or Company Name. This will sync in the Company details automatically from the Companies House record.

The Companies House details can then be found in Karbon on the Details tab of an organisation contact, making it easier to find and review information regarding a client.

Please note: The search can only be performed for Active Companies (i.e. any Dissolved companies aren't included in the search results).

Import key contact information into Karbon

Connecting Karbon to Companies House allows you to import key information into your contacts (where you have the Company Registration Number saved):

  • Legal Name

  • Financial Year End Day

  • Financial Year End Month

  • Incorporation Date

  • Any Key Dates

  • Adds Officers to notes

  • Adds Accounts (next made up to, etc.) notes

  • Adds Statement Notes (Next statement date, etc.)

Once the import is complete, you will be able to see all of the information for a company by navigating to the contact and selecting Details > All Accounting Details.

Download .csv export of your client data from Companies House

You are also able to download a .CSV export of your client data from Companies House. The download contains two tabs:

Change Log

This tab highlights all of your clients who had details updated with the following columns:

  • Karbon Key

  • Organisation Name

  • Company Registration Number

  • Update Type

  • Old Value

  • New Value


This tab will contain the data for all of your clients. The export will contain the details listed below:

  • Karbon Key

  • Organisation Name

  • Company Registration Number

  • Accounts next Made Up To

  • Accounts Next Due

  • Accounts. Last Made Uo To

  • Confirmation Statement Next Made Up To

  • Confirmation Statement Next Due

  • Confirmation Statement Last Made Up to

Note: You can access the data for your last 5 imports.

Who can access the Companies House data?

Only team members with Admin permissions can access the settings to download the data in CSV format.

All team members who have access to the contacts will be able to see the data imported on individual contacts.


If you need help in setting up the integration with Companies House or bulk updating Company Registration Numbers, reach out to our support team and we will assist you.

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