It sounds to me that what you need is to set up a trust fund with you as the trustee. The trust can then dispense money for something like a house, pay bills when they become due and you can also set up regular payments for "pocket money". It has better security over simply a bank account in her name but to which you are both signatories because the advantage is that technically it would no longer be her money. However, it has the disadvantage that it is technically no longer her money so she may not agree to it. There are lots of legalities to it all though, so you really need to go and see a lawyer Calluna - with your mum. There is no point going into any of this if she isn't going to be on board. You will have absolutely no chance of having her declared mentally incompetent. Even families with seriously mentally incompetent people still have enormous problems getting their loved one declared incompetent so they can step in, and from what you've said, your mum is just financially very immature.