Hi all,
I'm an Italian guy working with a permanent contract in Geneva, with 5 years B permit.
I'm going to move to the UK (I don't know for how long) but I'll continue to work full time remotely for my current Swiss employer, with some meetings here in Geneva.

I'm asking you: what is the best and legal way to do that from a bureaucratic and financial point of view?

My Swiss boss suggests me to keep the Swiss residency, the work permit and the current contract.
Is it possible? Is it legal?
I won't have any job in the UK and to be honest I don't see any "ethic" or legal problems in doing so, because actually I would behave as a Swiss resident really working in the UK.
I know that when I settle in the UK I will become UK resident, but that doesn't exclude that I can still keep the residency and work permit here in Geneva, as the Swiss law is different and doesn't require a minimum amount of days in Switzerland to be considered as a resident, am I right?
In case it's possible to keep the residency here, which address may I use for the working permit? Can I sublet my current apartment (legally) and still use the address for residency (legally)? Should I sublet only one room? Can I use a postbox at the Post? I don't have strong friends here for an address and I guess that it's not possible to use my company's one.

Another way would be to open a Ltd in the UK: is it managing the taxation something doable or is it something to be discouraged? Which kind of taxes would I pay: the Swiss one or the UK one? Has any UK contractor worked using his Ltd or using a Swiss umbrella one?

You don't need to keep anything here. If you are on a 'C' permit you can apply to leave Switzerland for up to 4 years, just read the back of your permit.

If you have a 'B' permit, you will have to start all over again when you want to come back.

Unemployment benefit

I've reading it and it says that if I announce my departure of if I'm absent for 6 months from Switzerland, my permit is cancelled.
But I'm supposed to come back here in Geneva every month, for team meetings etc.. the company I'm employee for is here therefore I still don't understand if I can consider myself as a resident here, which would be quite simpler than opening a Ltd in the UK.
I won't be absent for 6 months and therefore it doesn't seem to apply to my case, does it?

If you are resident in the UK for more than 90 days per year over a rolling 4 year period, or 183 days in one particular year (thereabouts - you can find the exact criteria on www.hmrc.gov.uk - there are other wrinkles, but this is the basics), then you are resident for tax purposes, and must pay income tax in the UK.

If you are earning money by consulting, for example, then strictly speaking your employer must set up a UK subsidiary to pay you. They must pay UK corporation tax on whatever profits their employee (you) generate for them in the UK. They must deduct NI and account for PAYE on your behalf.

If you are not actually generating income for your employer in the UK, merely working remotely for them, then there are three possibilities I see:

1. Your employer pays you in the UK and operate PAYE on your behalf. Not sure about NI.
2. You set up a ltd. company which costs less than £100. Your employer is now your client, and pays your ltd. company fees. From that you take a small salary - accounting for PAYE and NI yourself - and declare dividends every now and then (which you only pay income tax on - not NI). The contract must be drawn up to be a contract of services, not a contract for service, otherwise, you'll be caught by IR35, and all your income (less 5%) will be tax as salary.
3. You operate as a self-employed sole trader to your employer.

If you retain residency in Switzerland, then there may be additional liability - for example social contributions, or even income tax. However, there are tax treaties between the two countries, so you'll only be taxed at the higher rate of the two countries overall - most likely, the UK.

You and your company need professional advice.

When you leave your Swiss accommodation you need to deregister. If you don't your landlord should inform the authorities. The new tenants / owners of your accommodation will register and the authorities will wonder where you are.

In short it is not possible to live in the UK and remain a Swiss resident. Even if you wangle it, you may well end up paying tax in both countries. I don't see the advantage in what you want to achieve...

It is even more complex than this, since he/she will probably qualify as a non-dom for tax purposes.

Check out some of these links.
http://www.hmrc.gov.uk/cnr/hmrc6.pdf
http://www.hmrc.gov.uk/international/domicile.htm
http://www.hmrc.gov.uk/international/residence.htm#3
http://www.hmrc.gov.uk/international/remittance.htm

As stated by NAT, this is a complex issue and you and your company should seek professional advice.

It's my boss that wants to do that, I don't know why; I just guess that he sees fewer issues in doing that than in making me open a Ltd in the UK.
I think that I've got what the issues are from the UK point of view: reading from the gov sites it seems that I would be resident in the UK, not domiciled in the UK and earning money overseas from a not UK company, which means that I have to pay taxes only for the "earning I bring in the UK" which I don't have perfectly clear what it means, but I guess that if I transfer money to the UK they will simply tax me for that, but I don't know if even for withdrawals they can do that.

Instead, from a Swiss point of view, I don't understand if there is a law that sets a minimum number of days you have to stay here in order to be considered resident.
Theoretically it seems to me fully possible to have double residency.

After having asked to accountants here, they said that there are many people (even politicians) living elsewhere and maintaining their residency here, simply because they have their work and an apartment here (=a residential address).
In my case I would probably sublet a room (if it's legal) and using the other one when I come back here for meetings.

I don't get yet why the boss wants to follow this weird path (and I don't want any hassles); I'd prefer a B2B relationship using a Ltd for me, although I know that from a taxation point of view Switzerland is better than the UK.