My question is, my wife is the durable power of attorney for her mom. She is in a nursing is it legal for my wife to use her moms ssi money for her own personal gain, can she write checks to her self and then sigb her moms name

With a POA, your wife can certainly endorse those checks. If she is paying her mom's bills, I'm not sure if anything criminal is going on here. At most, her mom might be able to sue her for violating her fiduciary responsibility.

Usually a "durable" power of attorney refers to living wills and the authority to make decisions regarding the administering or withholding of medical treatment when the loved one for whom power of attorney is exercised is incapable of making such decisions for him/herself. What you're describing sounds like a "general" power of attorney. If your wife has been given this, then yes, she can legally sign her name to her mother's checks. However, taking her mother's money for her own personal use is questionably unethical if not illegal. As general power of attorney for her mother, if in fact she is, she should only be signing her mother's checks for her mother's expenses, not her own.

I was under the understanding from SSI that they do NOT accept POAs. They require that you be named Representative Payee. You wife will have to go into the local SSI office and be named Representative Payee. They also require that you submit records of how the money is spent.
I know this because I am Rep. Payee for my grandmother. They would not accept the durable POA that I have. I had to go through an interview with SSI and they had to do research to see that I was the right person for the job.

The above answer is correct-you will also need to keep an absolute accounting of the monies spent and open an account in both names-the recipient and the rep payee. Also, please keep in mind that no SSI recipient can have cash assets over $2000.00. Social Security has a list of what rep payees can spend money on. If she is in a nursing home, it is usuallly advisable for the facility to be the rep payee. If it is a state or federal funded facility, mom may no longer be eligible for benefits as SSI is not payable to claimants who are "incarcerated". It is, however, against SSA regulations for your wife to be using the money for herself unless it is for repayment of money that she has already spent on your mother-you will never know when SSA will knock on the door asking for a bank statement.