As Wray suggests, the EITC law was written to require SSNs for all parties precisely to reduce the possibility of fraud.I want to focus on the other part of Wray's answer, to re-emphasize that your spouse needs to have a tax ID number - an ITIN if she does not qualify for an SSN. Since she qualifies as a resident alien under the substantial presence test, she has all of the obligations of a US citizen under the tax laws. While you still can't claim the EITC you can at least file a joint return with the higher standard deduction and perhaps be eligible for other benefits not available to you as MFS.