In the Joint Election to Split Pension Income 2019 version, all the lines are named with letters such as Line A, Line B, Line C, and so on. In the 2021 version of the Joint Election to Split Pension Income form, All the lines are numbered such as Line 1, Line 2, etc.
In this case, Line A (2019 version) matches up with Line 1 (2021 version) and Line O (2019 version) matches up with Line 30 on the 2021 version.
Here is a link to the 2019 version: https://www.canada.ca/content/dam/cra-arc/formspubs/pbg/t1032/t1032-fill-19e.pdf. Here is a link to the 2021 version https://www.canada.ca/content/dam/cra-arc/formspubs/pbg/t1032/t1032-21e.pdf
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