So what do you think an entity in business is? You posted it. There are many places that define an IC as a person or entity. The businesses that OP hires are independent contractors. The laborers that the IC hires are subcontractors.
Aside from the shot across the bow, what is your point?
"The businesses that the OP hires can be referred to as ICs or as subcontractors. The labourers that the ICs/subcontractors hire are employees."
Because while not all ICs are subcontractors, and not all subcontractors are ICs, in this particular case the labels are interchangeable. And because OP said the IC/subcontractors' labourers are employees. (And as it seems you are unaware of this - employees and ICs are not the same. Ever. Hope this helps you along your learning curve!)
You can call them subcontractors but they are legally ICs. They are independent companies or individuals that work off site from the OP's company preforming work that the OP's company does not do themselves. He has no control of their work hours, he does not have control over what they do, they do not use equipment supplied by OP. They are ICs.
I have been reading case law and statutes on the differences between what is an independent contractor and what is an employee for the last two and half years. I don't think there is a relevant case that I haven't read.
You say: employees and ICs are not the same. That depends on the context in which your are referring to. Within a single company you can't have the same person being an IC and an employee at the same time. However, when a company contracts with an IC who has employees, then you have an employee working for the IC not the company that hired the IC.
Hope this helps you along your learning curve.
The argument is that you seem to believe that even though the OP is the one with the original contract, that the companies he contracts with to do the work are not subcontractors, which is dead wrong. I will concede that they might also be IC's, but they are definitely subcontractors. Therefore a subcontractor agreement is what is needed.
Nobody said that the people doing the work were OP's employees. Everyone said that they were the employees of the companies that the OP subbed the work out to.
The contractor hired the sub not the principal that hired the contractor.
For example: OP hires ABC Office cleaning service. ABC is an independent contractor. ABC then hires DEF because they cannot do the work. ABC subcontracted to DEF. That has nothing to do with ABC being an IC working for OP.
In this case OP is not a contractor. He operates a business that cleans offices. He is not hired as a contractor like you hire a contractor to renovate your home. He is the principal operating a business. When he hires other companies to do his work they are ICs. When the guy you (the principal) hired to renovate your home hires an electrician or a plumber, he is subcontracting to another company. You hired the contractor and he hired a contractor. If you directly hire the electrician, they are IC doing work for you. You do not have a contract with yourself.
Do you see the difference?
I hire a cleaning business to clean my offices (the OP in this instance). The cleaning company subs that cleaning job out to other companies. He is a contractor (the entity subject to the original contract) and the companies he contracts to do the work are his subcontractors.
I hire a home building company to build me a house. They sub out 50% of the work to other companies. Those companies are the home building company's subcontractors.
Both situations I outlined are the same premise. Any company that contracts to do work and then subs that work out to another company has subcontractors. Any individual or company that contracts to do work is a contractor. You are confusing yourself by the colloquial usage of the word contractor.
And before you embarrass yourself any further, keep in mind that I have more (accurate, legal) knowledge in my own little head about employees vs ICs than at least 90% of the regular responders here. This is my area of expertise. (So it's probably best if you kept quiet at this point.)
You go to the local mattress store to buy a new mattress. You sign a contract for the purchase. The store has an IC that delivers mattresses for them. Now you are saying that because you signed a contract to purchase from the store that the delivery company is a subcontractor? That is incorrect.
You like to post without any (ever) law to back up what you say. We are just obliged to accept what you post. You may be correct that you know at least more that 90% of the regular responders here. But I am among the 10% that are more knowledgeable on the subject of what an IC is than you.