The main factor to keep in mind is that any non-American contractor will have to be sponsored by the company utilising their services. There's no way around this and without sponsorship, UK-based professionals in IT or any other industry will have no chance of working in the USA.
Yes, a U.S. company can hire international workers abroad. However, hiring overseas employees comes with unique challenges, such as navigating foreign tax and employment regulations, correctly classifying international workers, and running global payroll.
It is possible to become a contractor in the UK as a foreigner; however, doing so is complicated. People have been considering options abroad for work, travel, and living more in recent years, so it is not surprising that there has also been a rise in overseas contracting.
Incorporating a US subsidiary typically is sufficient for a UK company to establish US operations. However, many US VC investors (particularly at the seed and Series A stages) will require a UK company to establish a US parent company before investing (the so -called “Delaware Flip”).
A contractor agreement should describe the scope of work, contract terms, contract duration, and the confidentiality agreement. It should also include a section for the two parties to sign and make the agreement official. If the contract doesn't meet these requirements, it may be inadmissible in a court of law.