I only really understand domicile from a UK perspective but here’s what I think the position is, based on my own research. Also you need to be careful how you use the term "domicile". As you'll see below domicile for UK inheritance purposes has a very specific meaning and doesn't mean "resident for UK income tax purposes".

UK inheritance tax only applies to those folks with a UK domicile at the point of transfer of assets (ie usually their death but may be at the time of certain lifetime gifts). UK law says people acquire a “domicile of origin” at birth which is the domicile of their father. So for a UK citizen born to a UK citizen father whose permanent home is in the UK, their domicile of origin is the UK. Once you have a domicile of origin, change of domicile for IHT purposes is not dictated by your citizenship or where you currently reside but by the concept of where you have your permanent home. In other words you may be living in France, you may pay taxes in France, yu may even have adopted French citizenship, but if it’s your intention to return to the UK at some point in the future to live indefinitely then you are deemed to have the UK as your permanent home and are still UK domiciled for UK inheritance taxes even though actually resident in France and even if you never actually return to he UK since it was never your intention to settle permanently in France. Equally foreign citizens who move to the UK can be treated as adopting a UK “domicile of choice” if it is their intention to live there indefinitely, even if you don’t take out UK citizenship. But just living there for a few years is not enough in itself, even if you are resident for UK income tax purposes, if you never intended to settle there permanently. So most foreign nationals who live in the UK for several years and then move on shouldn’t have anything to worry about as regards UK inheritance taxes, even if they were resident for UK income taxes during that period.

Under UK law a domicile of origin or a domicile of choice can only be lost by acquiring a new domicile of choice by going to live in another country with the intention of living there indefinitely. The burden of proof is on the individual to prove he had the intention of living abroad indefinitely. The issue is intent not fact. So if you move abroad but intend to retire back to the UK you will remain UK domiciled even if you live abroad for 50 years and die before you manage to return. So just having the intention to return keeps you in the UK IHT net, as would other “indicators” like maintaining a UK property whilst abroad, keeping a UK bank account, making regular visits, educating your children there, even having your body repatriated for burial. That’s what I meant by it’s possible for a UK citizen to lose their UK domicile for IHT purposes but it’s not easy and you have to make sacrifices. For most UK nationals, in order to lose your UK domicile you would have to live abroad for a number of years and demonstrate you never intended to go back by effectively cutting all links with the country - no home, no bank account (thought sterling offshore accounts are fine), restricted visits, no expressed intention of going back in letters etc, no burial in the UK.

In Switzerland, as in many other countries, there is no concept of domicile as in the UK. In Switzerland, if CH is your permanent home then you will be subject to Swiss inheritance taxes just by virtue of being resident when you die, regardless of your citzenship, domicile of origin/choice under your home country rules, intention of returning to your home country etc etc.

So as you can see it’s quite possible for a UK citizen who dies whilst a resident of CH to be hit by UK inheritance taxes and Swiss inheritance taxes since the UK applies a domicile test which has nothing to do with residence and CH apples a residence test which has nothing to do with domicile. Luckily there is a double tax treaty which means you can laim tax releif so your total bill will never be more than what it would have been oin the UK ie 40%.

In all of this it’s worth remembering that in the UK there are no inheritance taxes on the inheritance that pass between spouses. Also in the UK, taxes are not levied unless and to the extent that your assets exceed the tax free threshold which is a combined GBP 600,000 for married couples (increasing to GBP 700,000 by 2010).

In most parts of CH it's possible to arrange your affairs so there's no Inheritance tax on transfers between spouses. I say most parts because it's cantons which levy the taxes and rules vary. For example when I looked at this stuff Jura taxed transfers between spouses. I don't know if that's still the case. Rates of IHT also vary in CH between cantons but many have graduated bands which vary according to the beneficiary's relationship with the deceased.

If you are a foreign national living here then you need to check your home country rules to understand your individual tax position as regards inheritance taxes and whether there is a double tax treaty with CH to avoid a double hit. You also need to check the rules of your individual canton. If you are lucky enough to have enough assets where inheritance taxes are a consideration, it’s worth getting expert tax and estate planning advice.