Less than £1000 income for non-residents

I am a non-UK resident having been out of the UK for the entire tax year, but still a UK citizen. If my only UK based income is less than £1000 from interest/shares only, do I need to file a self assessment (SA)? I have filed SA for all previous years. If I don't need to file a SA, do I only need to tell HMRC via filling in the online form? Do I need to claim my allowances using a R43?

Hi,
For advice on whether you need to register for Self Assessment, please see link below.
Check if you need to send a Self Assessment tax return
Thank you.