If the person who needs to designate a POA cannot sign their name, I'd assume they are way too far along to be able to designate a POA. The person must be of sound mind and competent to designate a POA.
My reaction was the same as Angela's: if the person is too mentally impaired to sign his name, he cannot legally give power of attorney.
But physical incapacity is different. If, for example, the person can't sign because he is blind or physically disabled but is mentally unimpaired, there will be acceptable ways round this but you must find out what the additional legal requirements are.
I'm going to take exception as well to the issue of assumed lack of capacity. Some younger or older people may be legally and mentally competent but just have difficulty, for various reasons, in signing legibly. Someone with Parkinson's and shaking hands might fall into that category.
This is an issue to be discussed with the attorney who prepares the documentation, to ensure that an "x" is recognized legally in that state.
An acknowledgement (sometimes known as a jurat when an abbreviated version is used) might be appropriate to address this issue, even though acknowledgements are typically standard wording.
As my mother aged her shakiness and frailty coupled with vision loss made it a real ordeal to sign her name. (And why is the signature area so small on some forms anyway??) Unless the person has totally lost all function in their hands or never learned to write I would encourage you to get them to try to sign their name, it might not be pretty and it might stray over the lines, but I think it would still be better accepted than an X.
Cadimary, are you using an Elder Law attorney? If yes, then if the attorney deems the person competent to sign, using an X is acceptable only if the signer is unable to write their legal name due to issues with their aging hands or if they never learned to write.
Angel
But physical incapacity is different. If, for example, the person can't sign because he is blind or physically disabled but is mentally unimpaired, there will be acceptable ways round this but you must find out what the additional legal requirements are.
This is an issue to be discussed with the attorney who prepares the documentation, to ensure that an "x" is recognized legally in that state.
An acknowledgement (sometimes known as a jurat when an abbreviated version is used) might be appropriate to address this issue, even though acknowledgements are typically standard wording.