Non-doms: the facts.

Non-doms are people who are "non-domiciled" in the UK for tax purposes because they have their permanent home abroad. The system dates back to the Napoleonic Wars.

There are an estimated 116,000 non-doms. British-born people can be classed as non-doms, inheriting their status from their father.

The upside is they can opt to pay tax only on income brought into Britain and pay none on their earnings or capital gains outside the country.

The downside is there are now levies for being a non-dom; up to £90,000 for one who has been resident here for 17 of the past 20 years.

It is estimated the levies will raise around £100m a year from 2016.

Labour wants effectively to scrap the non-dom status, meaning from next year everyone who makes Britain their permanent home pays tax in the same way; it says the change will raise several hundred millions of pounds.

But temporary residents such as students or workers coming to the UK for a limited period would be exempt.