My mother, who lives alone, does many things herself. Drives herself to chemotherapy, keeps her place tidy, cooks for herself, food shops and does a number of other things. But she's been making mistakes on her finances. Has much difficulty logging in to her online banking accounts (that I had set her up with a while back) and I feel isn't fit to take care of her finances. The cognitive decline is worsening but she does so much herself. I have power of attorney, but when do I step in and take over? She's terribly stubborn and completely closed off to reasoning. She still wants to control everything.
Your best bet is to set up a once a month meeting to go over mail and bills. If your Mom will allow this it makes it ever so much easier. I sure do wish you good luck, but sounds as tho eventually you will need to go for emergency temporary guardianship.
Do you have your name on moms checks and a dual checking account at the bank? Makes life much easier, let me tell you. If you have moms banking login info, you can keep an eye on things to make sure she's not getting scammed out of large sums of money,
See about getting her into her PCP for a checkup and mini cognitive exam. Her score will help determine where she's at in the impairment scale.
Good luck to you
How old is your Mom? Extreme and irrational stubbornness is often one of first signs of dementia/cognitive decline. You can attempt to get her tested but not sure it will be accurate if she has chemo brain, which can go away eventually. What kind of cancer does she have? What stage?
If you have Durable PoA I don't think you need a medical diagnosis of incapacity to step in. That's what I have with my Mom and she has gradually allowed me to take over more and more of her financial management. Now I do all of it.