Simulationsrechnungen zur Reform von Wohngeld, Kinderzuschlag und Grundsicherung

"In September 2025, a Commission on Social Welfare State Reform (KSR) was tasked with submitting a report on how social welfare structures could be modernized and de-bureaucratized - for the benefit of citizens and administrative bodies alike - while maintaining the level of social protection. To support the work of the commission, the ifo Institute and the Institute for Employment Research (IAB) conducted a comparative analysis of the effects of two fundamental reform approaches using behavioral microsimulation. The models developed by both institutes provide a detailed representation of the current tax and transfer system at the micro level, making it possible to calculate the impact of alternative policies on net income, benefit entitlements, and work incentives for various types of households. Both analyses are based on data from the Socio-Economic Panel (SOEP). This study is an excerpt from the BMAS research report “Mikrosimulation von Reformoptionen steuerfinanzierter Sozialleistungen” - commissioned by the KSR and produced in 2025/26 - and covers the analysis of reform approaches in which the IAB was directly involved. The full research report, along with all detailed results from both institutes documented in separate appendices, has been published by the Federal Ministry of Labour and Social Affairs. From Chapter 2 onwards, the text published here is identical to the corresponding sections of the main report (with the exception of links to the appendices). The introductory “In aller Kürze” section has been newly added. The first reform approach (Reform Approach 1) considers integrating housing benefit (Wohngeld) and the child supplement (Kinderzuschlag) into a reformed basic income support system (Grundsicherung) featuring modified rules on additional earned income under SGB II. The second reform approach (Reform Approach 2) envisages merging housing benefit and the child supplement or replacing them with a new upstream benefit. Benefits under SGB II and SGB XII remain in place but are supplemented by modified rules on additional earned income within SGB II. The two reform approaches and their associated scenarios were specified by the commissioning body and examined across a total of 84 reform variants. The aim of the analyses is not to provide a definitive political assessment of individual proposals, but rather to compare and classify their anticipated effects. In most variants, Reform Approach 1 results in fiscal savings but potentially leaves some of the affected households worse off than under the status quo. Significant positive effects on labour supply can be achieved with this Approach - particularly through differentiated rules for considering income in the means test based on partnership status and the number of children. Under Reform Approach 2, integrating the child supplement into the housing Benefit - while applying a separate benefit withdrawal rate for the child component within the housing Benefit - would likely yield modest fiscal savings alongside moderately positive effects on labour supply. Integrating the child component directly into the housing benefit formula would, according to model calculations, result in additional costs but also somewhat stronger positive impacts on labour supply. Merging the housing benefit and the child Supplement - using an income definition based on the rules for the child supplement or the Social Code Book II (SGB II) - would likely lead to moderately positive effects on labour supply and simultaneous fiscal savings, provided that lower incomes are subject to a high benefit withdrawal rate while higher incomes experience income gains. Conversely, strong positive effects on labour supply would only be expected if benefit withdrawal rates were significantly reduced - which would, however, entail substantial additional fiscal costs." (Author's abstract, IAB-Doku) ((en))