The Government are concerned that bringing external investors into a family business can dilute the founders down below a 5% stake in a company. The 5% threshold may therefore hold back the seeking of external funds and therefore hold back growth in a business.
These rates were always intended to rise over time but with so many other regulatory matters to keep up to date with, it seems that this is the appropriate time for a reminder of the imminent increases.
A practical consequence of an exit will be cessation of access to the parent-subsidiary directive and the interest and royalties directives. These directives are designed to allow for flow of funds between member states without withholding taxes. After March 2019 the terms of the tax treaty between the UK and the relevant counter party will govern the extent that withholding taxes will apply.