Hello - I have a client that recently got his SSN card and he will file his 2020 Tax return using his SSN. He wants to file previous taxes since 2014-2019 because he received payments with a 1099 Misc and he must report them, he never applied for an ITIN, those contractors only gave him the 1099 Misc with his full name, so he must file. Now my question is, does he need to apply for an ITIN just to file those years when he did not have a SSN? Or he can file those years usi