Contrary to popular belief, there is no legal requirement to have the electrical equipment in either the workplace or, in the case of any landlord, or company-supplied electrical equipment in rented accommodation, or residential care home etc., PAT Tested*.
However, there is a legal requirement under various Acts.
The following links provide further information.
Sellers of Second Hand Electrical Equipment
*NB. There is just one exception to this: Regulation 6 of The Provision and Use of Work Equipment Regulations 1998 (PUWER) requires that equipment has to be 'inspected' in work situations where the safety of the equipment depends specifically on the installation conditions, and, in particular, where conditions are liable to lead to deterioration. This is a very specific requirement, for a very specific situation, and yet even here, there is no mention of the word 'testing'.