Okay, so if I'm an overseas company that hasn't incorporated a UK subsidiary, what circumstances can mean that my business will be subject to tax in the UK?

Well, if you're deemed to be centrally managed and controlled in the UK, then the company is tax resident here.

Or if you're deemed to create a permanent establishment.

And what creates a permanent establishment? Well, at a high level, you're looking at two common routes.

First, a fixed place PE.

Having a place in the UK, an office, a workshop, sometimes even a home office, through which the business is carried on with a degree of permanence.

Second, a dependent agent PE.

You're trying to build a narrative that demonstrates if the UK activity were a standalone business, what profit would it earn for doing this work?