HMRC Employer Bulletin 90 for June 2021 contained the following article (missing from Agent Update):
Taxable benefit charge - returning office equipment
Employer provided equipment
If you have supplied your employees with office equipment to allow them to work from home, without a transfer of ownership, there is no tax charge when they return the equipment back to you. If you transfer the ownership of the equipment to the employee at any stage of their employment, a benefit charge generally arises on the market value of the equipment at the time of the transfer less any amount made good by the employee.
Employer reimbursed equipment
If your employee has agreed to purchase their own home office equipment for use whilst working at home as a result of coronavirus and you reimburse the exact expense, unless you have specified to your employee that they must transfer ownership to you, the ownership of the equipment rests with your employee.
There is no benefit charge on the reimbursement. There is also no benefit charge if you allow your employee to keep the equipment as it is something that they already own.
It's that last para (first sentence in it) that stuns me.
According to "the people who know these things" it is a temporary dispensation for last & current tax years - as part of supporting employers during the pandemic - so may be withdrawn at short notice. But, in the meantime, it provides a wonderful opportunity for small businesses trying to encourage a more permanent WFH culture - without employees bearing any tax burden IF the purchasing of equipment is done the right way round.