Trivial Benefits - £50 threshold based on benefit to employee or the cost to employer

Is the £50 trivial benefits threshold based on the benefit to the employee, or the cost to the employer? So, for example, if the employee receives £50 as a trivial benefit, but in delivering that, the cost to the employer is £51, is that still a trivial benefit, or is it taxable because it costs the employer £51?

Not hrmc but it is the cost of providing the benefit rather than the value of the benefit.

Hi,
When reviewing if any expense or benefit given to or provided to an employee is taxable it is always the cost to the employer.  
Thank you.