»The Concept of Income under Parental Benefit Law. On Tying the Determination of Income under Parental Allowance Law to Tax Law«: The paper deals with the concept of income in § 2 para. 1 sentence 3 BEEG, which refers to tax law to determine the income relevant for parental allowance. The link to tax law is intended to simplify the administrative procedure, but leads to delimitation difficulties and contradictions. The study is taken as an opportunity to work out a system of income concepts in social law and, on this basis, to submit a reform proposal for the current income concept.