Tartan tax is like when you have a cookie jar and you want to give some of your cookies to your friends. You might ask them to trade something for the cookies, like a toy or a sticker.
In Scotland, there is something called the tartan tax, which means that instead of cookies, the government wants some of your money to help pay for things like schools, roads, and hospitals.
But not everyone wants to give their money to the government, so they made a rule that people can choose if they want to pay the tartan tax or not. It's like if you had the choice to give your cookies to your friends or keep them all for yourself.
If people choose to pay the tartan tax, they will give some of their money to the government in addition to other taxes they might already pay. But if they don't want to pay the tartan tax, they don't have to, and they can keep their money.
It's like having a choice to share your cookies or keep them all for yourself, but with money and taxes instead.