This paper reviews the accounting frameworks underpinning the data inputs to the Comparative Migration and Settlement (CMS) task now that the majority of country studies are either published as IIASA Research Reports or are in the publication pipeline. Rigorous comparisons are made of accounting, sex, age, time, and regional definitions used in the CMS set of studies, and the methods used to estimate required model inputs from available data are described. These comparisons and descriptions should serve as required reading for researchers embarking on further analysis of the CMS task outputs or on any future exercise in comparing the spatial patterns of population change and movement in different countries.