“…Thereby, a high and thus competitive declaration has to be balanced with a solid financial strength of the company. Various mathematical models for the declaration mechanism are discussed in the literature, see, e.g., [2,6,10,14,15,22,24]. In [14,15,22], the bonus interest rate for the next year is already declared at the beginning of this year (principle of advance declaration) as it is required in some countries, e.g., Germany, by regulation.…”