Call the IRS on the IRS Practitioner Priority Line.

@Strongsilence-CPA If you get them on the phone, what would they do?

For return already filed - amend income to match the name/SS# on the return

For return not filed - change income to match the name/SS# on the return

add notes to the taxpayer accounts about the errors. 

The clients TRUE name is a set of numbers. If you only screwed up the first name, that will likely not create a problem. Report back when you find out for sure.