Accepting the OP KNOWS if he is a US citizen…
Do your parents have SSN? If not, you have to do a manual filing of the FAFSA. On that form, you put in 000-00-0000 for their SSNs, and you can manually put in the income.
It’s really likely you’ll be selected for verification by the school, and at that time you can explain the tax status. There is no way to do it on the FAFSA forms, on the computer or hard copies.