Happens all the time. I got one from a State once, and I'm still convinced I was right and they were wrong, I'm not exactly going to argue with them, when they'

Happens all the time. I got one from a State once, and I'm still convinced I was right and they were wrong, I'm not exactly going to argue with them, when they're sending me money. However if you report more interest, or wages than they know about they will take your numbers as is - they assume you are reporting under the table income. They will however fix arithmetic errors, and give you credit for things you should have asked for (dependent deductions for example).