The UK shows relatively high levels of progression to higher order birth compared to the rest of Europe. A number of explanations have been put forward to explain these patterns, including the way in which social assistance is strongly means-tested and targeted at low income parents within the UK’s liberal welfare system. It is not possible, given the recent policy context and with the available data, to identify causal associations between particular welfare policies and fertility outcomes. The aim of this paper is instead to identify the individual-level associations between household income, receipt of welfare benefits, housing, and the probability of progression to a second, third and fourth birth. We use nationally representative household panel data representative of the UK population between 2009 and 2014. Our findings highlight how the woman’s age strongly mediates relationships between socio-economic status and progression to further births, highlighting the importance of the social polarisation in the timing of entry into motherhood for our understanding of socio-economic gradients in completed family size. Net of the woman’s age and other controls, a positive relationship between income and progression to second and third birth emerges. Receipt of high levels of child tax credit is associated with an increased risk of third birth, but not fourth birth, whilst living in social housing shows a strong, positive association with both third and fourth birth.