On the last few pages of filing, surrounding the payment options, there are little green bubbles, or sentences in blue. Those places will answer questions that most people have asked regarding the area of filing that they're in. I had the same question, and one of those "help tips" explained why I had to pay separately, for State taxes, and federal taxes. There's also a question mark at the very top of the page, where you can type in questions, or key words, to questions other people have asked. Those two ways will help the most with any questions you may have. I'm not positive on how it explained the "why", so I don't want to write it on here, to you, and mess up the wording, only to confuse you more. I hope this helps 😊