Regulations §1.6012-1(a)(5) permits you to rely on a POA as authorization to sign a return for another person only if that person is unable to sign due to disease or injury, continuous absence from the United States for at least 60 days prior to the due date for filing, or if specific permission has been granted by the IRS. The POA must specifically state that you are given the authority to sign, and give the specific
reason why as listed above.