School funding per pupil increased substantially between 1999-00 and 2012-13 in England. It also became more varied across schools with higher levels of funds targeted at more deprived schools. Real-terms increases in funding per pupil were much larger for the most deprived group of primary and secondary schools (83% and 93%, respectively) as compared with the least deprived primary and secondary schools (56% and 59%). In this paper, we decompose these increases in funding per pupil into the amount explained by quantities of different types of staff per pupil, their price and changes in non-staffing costs. We find that some of these increases in funding per pupil translated into larger numbers of teachers per pupil and a higher real-terms cost per teacher (about 20-30% of the increase in funding per pupil). However, a much larger portion of the increases in funding can be accounted for by higher levels and increased variation in the use of teaching assistants (largely lower skilled staff), other non-teaching staff and non-staff inputs (such as learning resources, professional services and energy). Furthermore, there is also evidence to suggest that differences in expenditure between the most and least deprived schools are smaller than differences in funding, with more deprived secondary schools running slightly larger surpluses. Increased use of non-teaching staff was partly an intended policy shift by policymakers at the time. However, we argue that the scale of the changes in inputs are more likely to reflect rigidities, the flexibility of contracts and uncertainty over future funding allocations.