The Solvency II Framework distinguishes between an Insurance Holding Company (IHC), a Mixed Financial Holding Company (MFHC), and a Mixed Activities Insurance Holding company (MAIHC), where the IHC cannot be a MFHC;  and where the MAIHC should include at least one (re)insurance undertaking among its subsidiaries.
The definition and requirements set out in  Article 212 of the Solvency II Directive must be met in order for an undertaking, to be classified under either of the categories of holding companies. There are no predetermined quantitative triggers to reclassify from MFHC to IHC; nor to categorise a holding company as an IHC. Nonetheless, there is a quantitative component in the definitions that should be considered in the assessment both by industry and supervisors.  
Please also note that under the Solvency II Framework there is a clear differentiation regarding the calculation of capital requirements; and the calculation of own funds. In relation to the own fund treatment of strategic participations, please refer to Article 68 and 171 of the Delegated Regulations, and EIOPA-BoS-14/170 Guidelines on treatment of related undertakings, including participations.
An early engagement with the relevant National Competent Authority (NCA) is encouraged to discuss the implications of the case at hand. The Q&A in regulation aims to address focused questions on a particular issue of the Solvency II Framework; EIOPA cannot provide consultancy advice nor comment on individual cases subject to supervisory assessment.