treatment of income from trust funds

can someone advise please - I have a client who has Income Support as a lone parent of a five year old, she may be able to get income from a family trust fund. She has absolutely no access to the capital but payments may be made to her at the absolute discretion of the trustees. It is not a charitable or personal injury trust, nor is it one of the named funds - Macfarlane etc.

Am i right in thinking that regular payments made from such a fund can be treated as voluntary payments and so disregarded (if so is there a limit to the amount that may be paid?) and that irregular payments may be made and those should be treated as capital?

If this is the case could someone quote the regs for me please?

Are there any definitive circumstances in which the income from a trust fund like this be accountable - i.e. could a dm interpret the regs in different ways?

Thanks in advance for any advice

I have always understood that payments of income from a discretionary trust would be income. Certainly for tax purposes they are, and are subject to taxation in the hands of the beneficiary: the trustees must deduct tax at source before paying it, rather like PAYE