This report estimates the monetary impact of one day of school absence within state-funded English secondary schools. First, the authors model the association between absence in Years 7-11 and Key Stage 4 attainment. Then, they apply these results to previous departmental research on the lifetime earnings returns to education. Combining these results enables the authors to estimate the effect of increased absence from school on reduced future earnings for individuals. The findings are consistent with previous departmental research in this area, which found pupils who had between 95-100% attendance in Year 11 were 1.9 times more likely to achieve a Grade 5 in English and Maths GCSE compared to pupils who only attended 90-95% of the time. The motivation behind this analysis is to obtain a monetised figure which could be included in cost benefit analysis calculations for policies aimed at reducing school absenteeism or where school attendance might be impacted. Additionally, the estimates within this paper can also underpin discussions on the importance of attending school, highlighting how this can affect skills and human capital in the economy.