You have to use a fake ITIN, try 999-88–9999. Then, print and sign your tax return. Use some white out to erase the fake ITIN. Mail your tax return along with the W7 ITIN application form to the address in the W7 instructions. After the IRS issues the ITIN, they will forward your tax return for processing.
You won’t be able to file your state return right away. After you receive the ITIN in the mail, update your account, then print, sign, and mail your state return.
Thanks! The previous answer worked, but this is the exact answer I was looking for.
If you are a US citizen and your spouse does not have a Social Security number or an ITIN and you are not applying for an ITIN with the tax return then you can only file your tax return as Married Filing Separately. Where asked to enter the spouse's Social Security number enter 999-88-9999. You can only print and mail your tax return, it cannot be e-filed. When you print the tax return erase the Social Security number for your spouse and manually enter NRA for non-resident alien.
See this TurboTax support FAQ for the procedure to print and mail a tax return using the online editions - https://ttlc.intuit.com/questions/1944348-how-do-i-print-and-mail-my-return-in-turbotax-online