IFAC are shocked by the imperialist ambition of EU refusing to grant equivalent access to UK firms in EU.
The Americans get a better deal than we do!
IFAC put together an article on what you can and cannot do in EEA and USA post BREXIT.
You'll be surprised to find out how BREXIT has made it easier in many ways than before, at least for IFAs.
Yes, you can continue to advise the client, and can continue to charge him for the advice.
The advice will be regulated by the FCA. They regulate UK firms, and the location of the advice is not their consideration.
The advice will be covered by FOS, even though he is non resident. (link to fos)
The advice will be covered by FSCS even though he is non resident . (link to FSCS)
Other considerations
Yes, you can continue to advise the client while they remain in the USA. The advice can be delivered across border, and you do not need to buddy up to a USA adviser under any UK legislation. There are UK advisers with USA links, who specialise in advising USA resident customers, as particular expertise is usually required for USA taxes are worldwide, regardless of residence.
The advice will be regulated by the FCA. They regulate UK firms, and the location of the advice is not their consideration.
The advice will be covered by FOS, even though he is non resident.
The advice will be covered by FSCS even though he is non resident .
Other considerations
IFAC confirm that there are no restriction on the firm advising non-residents with links to a local adviser.
Where complaints are directed, it will soon become apparent to the complainant that the UK firm’s liability extends to all aspects of the advice, not just the small portion attributable directly to them.
The advice delivery across border, whether by email, zoom or phone, will be regulated by the FCA.