undercover reporting

[samuel23]

Not sure if this the right section to post this but here goes - When an undercover reporter is working at a job (or even if a police officer is working undercover on a job) what happens to the money they earn?. As they are already employed and getting paid for it, how do they go about paying the tax / national insurance on the money they earn? To be employed they have to give over their details, so where do they get their info from? Are they supplied with false credentials, and if so isn't this illegal?