If an existing trading company is to become dormant, you must notify the Companies House about upcoming dormancy and file accounts to the HMRC for the part of the year when the company has been active. A dormant company must not have any debtors and outstanding incoming payments and there must be no transaction on its bank account.
In the next accounting period, a dormant company must file dormant accounts to the Companies House and nil tax returns to the HMRC. Besides, make sure that your Confirmation statement has all the required information such as a registered address, SIC codes, details of shareholders and directors, issued shares and where incorporation documents are kept.
The same applies to a company that has been dormant from incorporation including filing nil tax returns to the HMRC at the end of each reporting year.
If there has been a change in shareholding or directors of a dormant company, in the size of its share capital or anything else, you must notify the Companies House as soon as possible. A company secretary can take care of all that.