Pensioner - Self Assessment verses Self Employment

I am a pensioner whose sole (taxable) income has been via the state pension for the last 5 years. I am considering doing some work on a regular basis for a charity. They would pay me a regular amount every three months. Can I do this via a self assessment form (using the other earnings box) or would I have to register as 'self-employed'? Is there a limit on the amount that would impact the above?

Hi Ken Ewer,
It would depend if the charity are treating you as an employee or as self employed.
If self employed and your income will be a £1000 or more then you would need to register as self employed and complete a Self Assessment tax return:
Set up as self-employed (a 'sole trader'): step by step
Thank you.