The Family 500+ programme, introduced in Poland in 2016, significantly increased the disposable income of households with children, thereby potentially affecting household consumption. We estimate cohort-specific smooth transition models based on adjusted Household Budget Survey data to assess short- and medium-term changes in income elasticities and interest rate semi-elasticities of consumption within four household types defined by the number of adults and children. The analysis focuses on changes following major expansions in social assistance, capturing potential regime shifts in consumption. The findings underscore the importance of household heterogeneity in assessing the macroeconomic impact of large-scale social transfers. The results reveal that only the lowest-income-per-capita, single-adult households, regardless of the number of children, exhibited a significant increase in average income elasticity of consumption, rising from about 1.0 to 1.2 after the programme’s implementation. The change in other groups was limited (families with three or more children), while income elasticity remained unchanged (families with one or two children). Although the effects of additional income indicate adjustments in consumption, their aggregate contribution to total consumption was limited, given the relatively small share of low-income-per-capita households in overall demand. Consequently, the programme did not generate a noticeable rise in the aggregate consumption multiplier. In addition, the analysis identifies divergent changes in interest rate semi-elasticities of consumption which may reflect changes in credit access or substitution between debt-financed and transfer-financed consumption.