When you incorporate your limited company or limited liability partnership, you will receive a letter form Companies House shortly after with your companies House Authentication Code on it. You MUST keep it safe. It is what is required in order to submit any statutory filings such as your Year End Accounts and your Confirmation Statement. It will also be required if you need to change any details with Companies House such as a new director, a change of address, or an amendment to shareholdings.
If you become a client of ours, you will need to share this authentication code with us which shows that we have permission to file on your behalf. If you have misplaced the code, you can request a new one by going to the Companies House website. It will take 10 days for a new one to be sent out.