Having an assistant, but not registering as an employer

[Mouse]

I'm going to have an assistant start soon, just for a few hours and will be paying them £40 a week, rising to £100 a week later in the year.

I looked into registering as an employer but it said I don't need to if they're earning less than £116 a week. That seems good news, but what do I do about declaring their earnings? The government website just said I need to keep a record of what I'd paid them. How do they go about declaring their earnings? They don't have another job, so won't need to pay tax or NI, but surely they need to declare it somewhere?

Anyone got any experience before I phone HMRC?

[moggy]

any thing here? There are more documents about assistants, search in Free Resources here.
assistant forms

[sarah707]

They invoice you and you pay them and put it through your books as an expense.

they record their income and do a self-employment tax return