An H-1B employment visa, most likely, since it sounds like you'll be doing productive work in the US. You won't be able to use a visa waiver or B1 business visa (for those that cannot obtain a visa waiver). There's a common misconception that you can simply travel to the US to work for short periods without an employment visa - you cannot for anything that is classed as "productive work", except for a small number of edge cases/exemptions. For the avoidance of doubt, employment means you being an employee of a US company who will sponsor your visa.
Obviously, none of that is going to happen for a short assignment.
You may be able to organise only "non-productive" work in the US. I wouldn't recommend that you blag it or lie at the port of entry, assuming you value your ability to enter the US in future.
> Invoicing and getting paid as a UK company invoicing a US company
If you were able to conduct all the work in the UK or to only conduct non-productive work in the US (such as meetings (
) ), then YourCo would invoice the US company like any other company. YourCo would be paid as normal into any bank account you choose.> Tax / VAT
There is no witholding requirement for non-US source payments to a non-US person. You may be asked to complete a W8-BEN-E for your business, to certify status. You should mark your invoices as outside of the scope of UK VAT (assuming they are, and they most likely are, except for some edge cases).
You didn't ask about insurance, but you probably should've done. You will need specialist insurance (not cheap), depending on the jurisdiction and governing law of the contract.

Leave a comment: