Originally Posted by
h15t0r1an
Not true. In the UK whilst working as a student, I waitressed. I was taxed according to the rate of tips received by waiters at that location, as assessed by the Inland Revenue. Depending on the day, I might not actually make those tips. e.g. if I had a lot of German or Japanese customers, who don't tip. Australians were also largely notorious for not tipping, even when they knew the employer in the UK expects wages to be made up to liveable to tipping. So I'm the one that's done it and is now on flyertalk. Trust me it's true.
You are not ever taxed in the UK on what you could have earned or should have earned. You are taxed on what you declare you have earned. You may have been on an emergency tax code where you were paying an amount designed to exceed what you would owe. This would be on the assumption that you would claim back excess payments at the end of the year or pay a reduced rate if you sorted out your tax code. Alternatively, your employer may have been scamming you.