One of the simplest extensions of the Standard Model is the Two-Higgs-Doublet Model (2HDM), which can serve as a test model to explore a Higgs sector with additional neutral and charged
Higgs bosons. For specific types of the 2HDM, predictions including higher-order corrections and, hence, also the renormalisation procedure have been discussed from different perspectives.
The renormalisation of the general 2HDM has received less attention so far. One reason is that the general version suffers from strong experimental constraints. Our motivation to study the general
2HDM is the following: On the one hand, a general 2HDM naturally contains the specific versions of the 2HDM so that, in principle, calculations done in the general 2HDM can easily be applied
to specific versions. On the other hand, a specific choice of parameterisation and a corresponding renormalisation scheme may not be suitable to describe certain regions of parameter space that
can be identified with a particular version of the 2HDM. For example, singularities in the relations between the original parameters and the parameters of the chosen parameterisation can occur. Hence, the general 2HDM is also a good test model for different renormalisation schemes and their overall applicability.

In these proceedings, first, the general 2HDM and our choice of input parameters will be discussed. In a second step, we will discuss the choice of renormalisation conditions and apply them to physical
observables such as the partial decay width of a heavier Higgs boson decaying into lighter ones.