Carbon and beryllium migration within JET has been measured by post-mortem analysis of divertor and main chamber tiles removed after 2-3 year periods of plasma operation in JET. Impurity sources and screening have also been studied in individual pulses using puffs of CD4 to provide a calibration for the spectroscopic sources. In this paper, we discuss the consistency of the deposition measured in the divertor with the spectroscopically determined sources integrated over the relevant periods of operation.