strictly speaking its not as simple as this

generally if he's working in the same place for the same person using your tools equipment and materials on a regular basis he's an employee.
some people get away with it, others get stomped on by HMRC.
I had a subcontractor come to work for us, he had his own separate company, and came in on an ad hoc basis, or completed the work at his own workshop with materials I supplied, and he invoiced me with A VAT number. That we could
just get away with.
This is what HMRC say: I've highlighted the relevant parts.
(QUOTE)
You are probably self-employed if you:
run your own business and take responsibility for its success or failure
have several customers at the same time
can decide how, when and where you do your work
are free to hire other people to do the work for you or help you at your own expense
provide the main items of equipment to do your work
You are probably employed if you:
have to do the work yourself
work for one person at a time,
who is in charge of what you do and takes on the risks of the business
can be told how, when and where you do your work
have to work a set amount of hours
are paid a regular amount according to the hours you work, and get paid for working overtime - even if you do casual or part-time work, you can still be employed
You can also be employed and self-employed at the same time, perhaps by working for an employer during the day and running your own business in the evenings. Think about each contract separately - you may find that you are self-employed for one but employed for another.
There's no legal definition of employment or self-employment, so if there's doubt about someone's employment status the decision is made by referring to previous judgments - known as 'case law'. Whether you are employed or self-employed depends upon the facts of your working arrangements, what your contract says, or a combination of both.
anyway, someone will probably come along and tell you what you actually want to hear any minute.
But you will probably find that its simpler to treat him as an employee, on a zero hours contract, and not spend your time skating around grey areas of thin ice with HMRC. You actually have an employee, imho, you should be deducting his tax and national insurance, because if this guy fails to pay his tax or has other dealings (or problems) with HMRC you will come into in the spotlight as well, and they will want to get the tax and NI due from the easiest possible route, which will then be you.
HMRC can be fickle. All you need is a local "clampdown" and people who employ casual labour on a self employed basis are the prime targets, becaus ethey get two for the price of one.
plus if the guy later decides he doesn't want to pay the tax he owes HMRC, he can simply get it to HMRC compliance office to look at, who will decide that you are his employer, and you owe them tax, and interest, and penalties, and you are then the one in trouble for trying to evade tax.
But what do I know, none of this has ever happened to me.... has it???