Just so you folks know, the reality is, when e-filing a deceased taxpayer's return, it's not at all uncommon for the e-file to be rejected with an "SSN LOCKED" rejection message. If that happens, you have no choice but to print, sign and mail the return to the IRS. The person signing it will need to include documentation authorizing them to sign on the deceased behalf. Generally, the court order appointing or recognizing them as the representative of the deceased person's estate is fine. If a refund is due, then IRS Form 1310 will also need to be included. Get that at <a rel="nofollow" target="_blank" href="https://www.irs.gov/pub/irs-pdf/f1310.pdf">https://www.irs.gov/pub/irs-pdf/f1310.pdf</a>
If you get the SSN LOCKED rejection, that's actually a good sign. It means that whoever handled the final affairs did their job. The SSN has been locked so as to prevent fraudulent use. If you are able to successfully e-file, then after doing so you should contact the Social Security Administration to report their passing, and have their SSN locked permanently.