This is purely hypothetical!
So I have a person, I pay them £10 a month for the 1 hour's work they do me. I would assume no PAYE scheme is needed as, frankly, no tax, no NIC. But if I up their hours, at what point do I need a PAYE scheme? When they hit the first NIC threshold?
As a side query, I up their pay to £30 a month, but I find out they have a large recurring taxable but untaxed source of income (a state pension say, for some reason it is £20,000) which makes their total income over the PA (but their pay under all the thresholds). Is a PAYE scheme needed given tax should be being deducted from the employment?
I hope I haven't strayed too far from reality that my question is too complex, all I really want to know is, what triggers the need for a payroll? HMRC seem intent on bombarding me with how to do it online, but not whether it needs doing in the first place.