A nonresident spouse does need an ITIN -- that's exactly what the ITIN is for. It's part of the IRS's security system to make sure tax returns are filed by real people.
NRA is only acceptable for a return where the application for an ITIN (Form W-7) accompanies the return but the ITIN hasn't been issued yet. It is not a substitute for providing the required identification.
IRS issues Individual Tax Identification Numbers, or ITINs to foreign nationals and others who have federal tax reporting or filing requirements and do not qualify for SSNs. A non-resident alien individual not eligible for a SSN who is required to file a U.S. tax return needs an ITIN. Unlike other forms of ID, ITINs only have one purpose -- tax filing and reporting.
