Important:
This answer is based on tax law for the tax year ending 28 February 2020.
Answer:
In terms of paragraph 2, if the notice (we used number 600 for 2018, the following persons must submit an income tax return:
…;
every trust which is a resident; …
The notice makes no reference to an amount of gross income, as does for companies. We therefore agree with you – the return must be submitted until the trust ceases to be person (when it is revoked).