TAS 2022 includes performance-related data, ratios and other information for the fiscal years 2018, 2019 and 2020. The 2018 and 2019 data was collected through the 2020 ISORA survey and already included in TAS 2021. However, a number of administrations updated some of their 2018 and 2019 data during the process of producing the 2022 edition of the TAS. For that reason, there might be some differences between TAS 2021 and 2022 figures and tables displaying 2018 and 2019 data.
In certain areas, TAS 2022 also uses data from the 2016 and 2018 ISORA rounds to show trends for the period between 2014 and 2020. However, as noted above, the changes in the ISORA process meant that the ISORA 2020 and 2021 surveys have been reduced significantly in size when compared to the 2016 and 2018 version. In addition, following the review, a number of changes were made to questions to improve clarity and data quality. Therefore, care needs to be taken when comparing results from ISORA 2020 and 2021 with ISORA 2016 and 2018, and the wording of survey questions compared whenever relevant. The survey questions can be accessed on https://data.rafit.org/ under “Forms and Guides” in the section “Publication/Links”.
As a result of the changes to the ISORA survey, TAS 2022 may not comment on certain data points that were covered in the 2019 edition of the TAS (OECD, 2019[4]). For those data points, the 2019 edition remains the most recent source.
Also, it should be noted that statistical data is often subject to revisions after publication. As a result, some data may not correspond to what has been published by administrations. For example, it may be that opening balances of a specific year (t) may not correspond to closing balances of the preceding year (t-1) that were published in earlier editions of this publication.
Even more care should be taken when comparing ISORA data with data gathered through pre-ISORA surveys, i.e. data included in the sixth and prior editions of the TAS. When the ISORA survey was initially created and at the request of survey participants, the four partner organisations made considerable effort to agree and document a range of words and terms used in the survey and their meaning. While this has improved data integrity and comparability between administrations, comparisons with pre-ISORA data may be limited as definitions may now exist for terms not previously defined, or in some instances, have changed.
Further, in relation to combined tax and customs administrations, it should be noted that the data in this publication refers to the tax administration activities of such administrations. The data may therefore not be directly comparable with key performance indicators published by them as these indicators may include both tax and customs related data.