The COVID-19 pandemic not only affected the health of millions of people across the country, but the accompanying disruption to economic life had impacts on the financial wellbeing of many households. This has been compounded by an ensuing cost of living crisis, with energy bills and food prices rising rapidly. This briefing, analysing survey responses from the first wave of the COVID Social Mobility & Opportunities (COSMO) study, uses the rich data collected directly from both COSMO participants and their parents to explore the financial circumstances of households with 16 year-old children during the pandemic period. It allows a better understanding of which groups were most affected, and also provides the opportunity to link information on household financial circumstances with data on school attainment and the mental health of families. [For the fifth brief, "Health Impacts and Behaviours," see ED628603.]