evidence: Following the outputs of the Census in 2021, HM Treasury and the Welsh Government have also taken account of revisions to population estimates for this reconciliation. Population estimates are integral to the calculation of the BGAs, as they inform an assessment of the comparability of tax revenues in Wales and the rest of the UK at the point of devolving a tax, and the indexation of the Block Grant Adjustment over time. In light of the Census in 2021, the Office for National Statistics and the Northern Ireland Statistics and Research Agency have published rebased estimates of the population in England/Wales and Northern Ireland respectively, between 2012 to 2020. HM Treasury and the Welsh Government have consequently updated the comparability factors used to calculate the Block Grant Adjustments to ensure that they reflect the most accurate understanding of relative population size at the point of tax devolution. The impact of this is shown in the tables below.