A shareholder list is sent to Companies House on a confirmation statement if there have been share transactions during the confirmation period. 

For more information on filing a confirmation statement please see How Do I File a Confirmation Statement?

The software identifies for you if transactions have been dated within the period which you are filing for. If there have been share transactions it will automatically include a list of shareholders on the CS01 sent to Companies House. 

However, where there are no share transactions dated within the confirmation period then the previously submitted shareholder list should still be correct, therefore a new list is not automatically included. 

In the situation of no transactions taking place, the final step of the confirmation statement filing process will allow you to include a full list of shareholders if preferred. 

Note: If the option to include a list does not appear, it is because transactions have taken place so a list will automatically be sent. You can identify the transactions on the Shareholders step of the confirmation statement process. 

Automated confirmation statement filings have a setting relating to including the list of shareholders, this can be applied when setting up a workflow. See How to set up Automated Confirmation Statement Workflows.