Is "you have got to be kidding me" different from "you're kidding"? How should I decide which one to use?

Native speaker’s answer
Rebecca
Good question! "You have got to be kidding me" is much more dramatic than "you're kidding" and is used when you don't believe someone is being truthful or when you think someone is ridiculous. "You're kidding" on the other hand expresses less doubt and is less dramatic. "You're kidding" can be used anytime you are questioning what someone has said to be true. "You have got to be kidding me" is also more informal and should only be used when someone wants to emphasize that what someone has said or done is utterly ridiculous. Ex: You have got to be kidding me. You brought your video games on the camping trip? Ex: You failed the test? You're kidding!