<p>you are allowed to estimate and sometimes estimates are wrong. If you erroneously got a free application (fee waiver) you might want to consider going the extra mile and sending money for the fee with a letter saying you were wrong on the income and hadn’t intended to get a fee waiver you weren’t entitled to get. Other than that, it sounds like ‘no harm, no foul’ and you can’t change it anyhow as far as I know. I wouldn’t think it was worth writing a letter about unless you got an unjustified benefit (the fee waiver). The FAFSA needs to be updated with actual numbers when you get them, from estimates, but I don’t think the application matters that much as long as you don’t get the fee waiver or an aid award based on that. (My kids didn’t even report income on that.) You could get in contact with the financial aid offices of the schools you applied to and ask, though, to get the ‘final word’ on it.</p>