The Government does not wish to encourage patent trolls, ie companies which acquire patents solely for litigation, licencing or preventing the use of the technology. So, to claim the tax relief, a patentee who has acquired the patent via assignment, or an exclusive licensee must be able to demonstrate that it has developed the invention. 

Development means the company, a predecessor in title, or a member of the corporate group must have done one of:

If you rely on the development by another group member you will need express written licences in place.

If you rely on the development by a predecessor the new patentee/assignee or licensee must continue research or development into the same technological field for not less than a year after acquisition. This means that companies purchasing a fully developed technology will not usually be able to benefit from Patent Box.

You will need to create and preserve evidence of the development activity, so make sure that you keep a log.

If the development conditions are met only because of the actions of another group member, there is a requirement for active management of the patent or its family. This management can include deciding where to maintain protection, granting licences and researching alternative uses.