Son activos que antes eran propiedad del contribuyente y de los que se deshizo total o parcialmente.

"Despite considerable opposition, the government has proceeded
with the introduction of the **pre-owned assets income tax charge** (POT). There has been some modification to the original proposals contained in the consultation document in December 2003, but the basic structure of POT remains unchanged. The legislation can be found in Finance Bill cl. 84 and Sch. 15.
In summary, the intention of the government is to impose an income tax charge on the benefits of enjoying ‘pre-owned assets’ from 6 April 2005 onwards. **Pre-owned assets** are broadly assets previously owned by the chargeable person and disposed of in whole or part since March 1986. Separate rules defining what counts as enjoyment and quantifying the chargeable benefits apply to land, chattels and intangible property. There
are certain limited exemptions and exclusions. There are transitional provisions to cover arrangements already made.
The Inland Revenue has published a summary of the responses to the consultation process with its own comments."

http://old.tax.org.uk/attach.pl/2538/1611/TA_012-015_0604.PD...