Most agricultural soils erode faster than new soil is formed, which leads to soil thinning. Here, we used a model simulation to investigate how soil erosion and soil thinning can alter topsoil properties and change its susceptibility to erosion. We found that soil profiles are sensitive to erosion-induced changes in the soil system, which mostly slow down soil thinning. These findings are likely to impact how we estimate soil lifespans and simulate long-term erosion dynamics.