CH225560 | How to do a compliance check: information powers: third party notice: groups: notice to parent to check one known subsidiary
From HM Revenue & Customs · Compliance Handbook
Where a notice is given to a parent to check the tax position of one known subsidiary the special rules set out at CH225510 do not apply. The usual rules about giving third party notices apply, see CH23620. In summary
If you decide to obtain the approval of the taxpayer rather than the tribunal, you must get the approval of the subsidiary
You must send the subsidiary a summary of reasons
Your notice must name the subsidiary that you are checking
A copy of the notice must be sent to the subsidiary.