Overseas pension arrears payment - which tax year?

helpful_hound

My late husband was in receipt of an Irish pension due to having lived and worked there for a number of years.  We since moved and settled in the UK, where I still live now.
After his death in July 2019 I became eligible for a Widows Pension from Ireland.  There were numerous delays in setting this up, and finally they have confirmed that I will receive pension payments backdated from 16/08/2019.
My question is regarding the taxation of this back-payment.  I understand that I must submit a self-assessment and pay income tax in the UK on the entire amount (as it is not taxed from Ireland). However...
1) is it too late to register for self-assessment for 2019/2020?
2) can it be included in my 2019/2020 tax return, even though I still have not actually received the lump-sum arrears payment, and when I do it will be during this 2020/2021 tax year?
The reason why I want to include it in 2019/2020 tax return is otherwise it will come out of my tax free allowance for 2020/2021 and I will end up paying more tax unnecessarily.
I hope I have explained it clearly, and thank you for taking the time to read and advise!

molerat

You can declare income from the past 4 years.

1 no

2 yes - if you have already submitted a 19/20 return you can amend it once you have received the payment.

https://www.gov.uk/undeclared-income

Probably worth giving HMRC a call once you receive it.

helpful_hound

Thanks molerat!!

xylophone

https://www.gov.uk/hmrc-internal-manuals/paye-manual/paye93091

helpful_hound

xylophone said:

https://www.gov.uk/hmrc-internal-manuals/paye-manual/paye93091

Thanks xylophone.  The text in that link seems to primarily refer to PAYE, even though the heading includes pension.  However if I understand the gist correcly it indicates that backdating the income and applying it toward previous years tax return is acceptable?