After submitting the first Confirmation Statement and paying the applicable Companies House fee then for the duration of the Payment Period the company can file additional Confirmation statements without charge.
For every company the Payment Period is 365 days starting from formation date or the made up to date of the last annual return filed, it is not possible to change the payment period. This is not to be confused with the confirmation date, which can be changed.
Filing a Confirmation Statement resets the date the next Confirmation Statement needs to be filed, but does not change the Payment Period.
Example:
A company formed 01/10/2021 has a payment period of 365 days from incorporation, this coincides with the first confirmation statement due date.
The company then chooses to file a CS01 early on 01/04/2022, the company will pay the Companies House fee and this charge covers all CS01 filings up to the original due date / payment period date of 01/10/2022. Any additional CS01's filed up to 01/10/2022 will have no charge from Companies House.
After 01/10/2022 the company will need to pay the Companies House fee again for the next filed CS01 and this payment would cover the company for all CS01's they wish to file up to 01/10/2023.