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Thanks for your response spudqueen. They can already do that, but I want to take it a step further with them - we have been doing as you suggested for the last couple of years - they are interested in being able to control their money and I am actively encouraging it. The sooner they learn how it all works the better. The intention is that by the time they reach high school, they will get their monthly allowance and it will be up to them to budget and manage that appropriately in order to buy their own clothes, mobile credit, entertainment etc. together with their school meals and transport.
By that time they will be old enough to get their own cashcard etc, but I would rather they had a couple of years of using it in a closely supervised manner under their belt before then.
It is amazing the decisions they already make when they see that it is their own money they are spending. They have opted to get a subcription for their weekly comic as that works out cheaper, they have put off getting some toys as they felt that they were a waste of money. I certainly don't get pestered in the shops to buy them things as they know if they want them, they need to buy it themselves. I am not mean, they get a generous allowance for their age and I do buy them things for good behaviour etc, but they understood pretty soon that when their allowance is gone it is gone and if they chose to spend the lot on a video game, they had to do without something else for a while until next "pay day".
Your right, I don't think that they are going to be able to get what I would like, so we will have to persevere for a while with spreadsheets or something. They do have a savings account that can be managed online, but obviously they can't spend the money directly from that. I think that I can probably just transfer money from their accounts to my account and hand them the cash as an interim measure for now.
Thanks again.