Okay kiddo, so a diploma tax is when you have to pay money to the government for getting a diploma or degree from school. It's kind of like when you have to pay for a toy at the store, but instead of a toy, it's for your diploma.
Now, not every country has a diploma tax, but some do. In those countries, you have to pay the tax when you graduate from high school, college, or university. It's usually a one-time fee, which means you only have to pay it once.
The reason why some countries have a diploma tax is because it helps the government pay for things like schools, teachers, and other education-related expenses. So even though it might seem strange to pay for something you earned by working hard, it's actually helping to fund more education for others in the future.
But don't worry, not every country has a diploma tax, and even if they do, it's usually not a lot of money. Plus, getting an education is super important and can help you in so many ways, like getting a good job and living a happy life. So keep working hard in school and don't worry too much about the diploma tax!