The template is divided in between obligations managed by underwriting year (R0010 to R0140) and obligations managed by accident year (R0150 to R0290). Undertakings are required to report data on an accident year or underwriting year basis, in accordance with any requirements of the National Supervisory Authority. If the National Supervisory Authority has not stipulated which to use then the undertaking may use accident or underwriting year according to how they manage each line of business, as defined in Annex I to Delegated Regulation (EU) 2015/35, provided that they use the same consistently, year on year.

This question is applicable mostly for non-life and annuities business. In life business, other than annuities, it is expected underwriting year. This choice is not related to how the best estimate is calculated and which item compose the best estimate but rather, when information is requested by years (or periods in case of S.29.04) in each year/period the contract relates to.