Whilst the chancellor has stated he will demonstrate "Britain is open for business" the changes to Entrepreneur's relief are not quite that simple.

“Personal Company” definition:

With immediate effect (i.e. for disposals on or after 29 October 2018) the definition of “personal company” is becoming more restrictive, so that in addition to the current requirements (for 5% shareholding conferring 5% voting rights), the individual must also be beneficially entitled to at least 5% of the distributable profits and 5% of the assets available for distribution on a winding up.

2 year holding period:

For disposals on or after 6 April 2019 the qualifying period of ownership will increase from 1 year to 2 years (apparently on the basis that a longer term holding is more characteristic of genuine entrepreneurial activity). This will apply to typical share disposals, but also other qualifying disposals, such as disposals of businesses by sole traders. There are transitional rules for businesses that ceased to trade before 29 October 2018 (which will continue to benefit from the 1 year holding period, even if there is a subsequent disposal after 6 April 2019).