(103)The specification of the circumstances in which capital add-ons may be imposed and the methodologies for their calculation should ensure that the use of capital add-ons is an effective and practicable supervisory tool for the protection of policy holders and beneficiaries through the calculation of a Solvency Capital Requirement which properly reflects the overall risk profile of the insurance or reinsurance undertaking. Capital add-on amounts have a numerically positive value. The specification should also take account of the need to develop consistent and common approaches for similar circumstances. To this end reference percentages and limits could be used as presumptions to assess deviations but should not detract from the main objective of setting add-ons appropriate to the insurance or reinsurance undertaking in question.