What is flat rate tax, when does it apply and who has to pay it?

What is flat rate tax, when does it apply and who has to pay it?

Flat value tax

Public transport subsidy

In the case of public transport, the flat value tax only applies with salary conversion. billyard calculates the flat value tax for each ticket individually.
Depending on the configuration of the company, the flat value tax is borne by the employer or the employee.

Food subsidy

The flat value tax is only charged for receipts below 10,04€. 
Depending on the configuration of the company, the flat value tax is borne by the employer or the employee.