<prompt> Human: They sent me a letter saying that they reviewed by 1040x I had to send in an amendment and they are saying I owe another 500. I can mail a check or pay online. Its not a scam, the letter is legit and the website is a .gov. The amendment process was a little weird and I probably did mess something up, so Im honestly not too surprised. The question is, they dont provide any explanation or reason on how they calculated the 500. Should I call and get it? Or should I just pay it?  <response>: Call the IRS and ask for an explanation. 