That seems to be correct: > About half of undocumented immigrants also file income tax returns, often using an Individual Taxpayer Identification Number (ITIN)

That seems to be correct: > About half of undocumented immigrants also file income tax returns, often using an Individual Taxpayer Identification Number (ITIN) in lieu of a Social Security Number. https://fiscalpolicy.org/wp-content/uploads/2021/02/Pathway-to-Citizenship-pdf.pdf https://fiscalpolicy.org/wp-content/uploads/2021/02/Pathway-... Searched ddg using: pathway toward citizenship income taxes history undocumented You could also try calling the IRS and tell them what you’re trying to do to help somebody and ask what the their preferred methods are. I’ve had occasionally good experiences calling major government offices and asking questions.