Gift aid donations treated as made in a prior year

Hello Can you please assist me with practical advice on the following issue. I am a higher rate Scottish taxpayer who claims gift aid on my self assessment return. I submitted my 2020-21 tax return on 29 January 2022. In this return I claimed relief on a £30 donation made on 31 January 2022 by completing the section Gift Aid payments made after 5 April 2021 but to be treated as if made in the year to 5 April 2021. I included the gift originally as I new it would be paid before the filing deadline of 31 January but I now realise I should have only included payments made by the date I submitted the return (29 January). Since this £30 was claimed in the 2020-21 tax return, I did not claim it in 2021-22. The result of this error is that I have overclaimed approximately £6 tax relief in 2020-21 and underclaimed £6 in 2021-22. As the 2020-21 return is now closed to amendment I understand my only option to correct this would be to amend 2021-22 to claim the extra £6 relief and the write to HMRC to disclose a £6 error in 2020-21 return. Can you confirm if this is the appropriate course of action or given that this error nets to nil across both years can it be left unadjusted?

Hi,
As one cancels out the other, you can leave as it is.
Thankyou.