When Alistair Darling announced that the ISA allowances were going to increase to £10,200, we applauded his action as one that might actually help people. And broadly speaking it has. The only issue is that he didn't bother asking the people that provide these products if what he wanted to do was feasible or sensible.

Under the new rules, those aged 50 or over can increase their ISA allowances from October this year. Then in April next year the rest of the population can increase their allowances. But why do it this way? Why stop a large section of the population from investing, and yet allow others to invest six months earlier?

We are sure there must be a reason for this, but the Treasury has not come up with one yet, except to say that they want to "phase in" the benefits over time.

The problem here is that making this type of change is very difficult for providers. It means a massive reprogramming of their systems, and millions of pounds in reprinting forms. It is all very well making a policy, but unless it can be implemented it can be totally pointless. In this case, it is clear that it will not be possible for people to take advantage of the new ISA allowances, simply because providers will not be able to deal with the change.