Have POA for finances but bank has its own form now what?

Insist that the bank have its attorney look at your POA. If it conforms to your state's requirements, there is no reason they should not accept it. If they still refuse, I agree with Pstegman, contact your state's banking regulators.

If your Mom is in assisted living, can't she sign the papers the bank is requesting? I know my husband had issues trying to use the POA. A few years ago, A financial company (who don't want to give up a person's money) wanted a POA dated with in 6 months which was ridiculous. He finally took the paper and had his mother sign it. If you have something signed from the doctor saying she in incompetent to sign that may also help.

It sounds as if whoever you're speaking to at the bank is being intentionally thick. But it probably isn't intentional, in fact: educate them. Keep insisting on going higher up the food chain until you encounter someone who knows what he's talking about.

Maybe send the bank a note indicating the situation in writing, with the incapacity letters that prove the POA is in full effect, and cc the people that pstegman mentioned. You'd certainly think you should be able fill out their forms and sign it as your name, POA for your mom's name. I suppose you could get Mom to make any kind of a mark possible on the form and have that notarized and make them happy; I had to do that with a form for my Dad once that I expalined in simple terms and he had no problem with. Social Security does not honor POA and they require you to get Representative Payee status instead, but I have not heard of banks being able to do that. My mom's did need incapacity letters before helping out with the sale of her home, and I was able to get those easily. We had to use a traveling notary to come to the assisted living facility for her to resign as trustee and make that part of it 100% kosher too.

Ask for the Branch Manager. If he won't recognize the POA, file a complaint with the state banking regulators or attorney general. That always gets their attention.