The bolded section indicates that you have to elect by 31 October to allocate the relief to the previous year.
Section 3.4 of the tax and duty manual states it explicitly. You must inform revenue by 31 October 2021 (or the extended filing deadline if you pay and file online) that you want to set the contribution against your 2020 tax.
Of course. All claims must be made within 4 years and ones allocating contributions to the year before they were paid must be made by 31 October of the year they were paid.Did you also spot that page 6 of the tax and duty manual states "A claim for tax relief must be made within four years of the end of the year of assessment in which a contribution is made or is treated as having been made."
So there we have it from the horse's mouth! QED, thread closed.
Not sure what I am being asked here? The first two posts in this thread explain it all pretty clearly.