I sort of see that point, but I don't think that effect would be all that significant. And you could tweak it by having a personal allowance for savings interest alone, meaning most people would not be discouraged from saving by it, but those living off interest would still be taxed.
We have started to have that from this tax year. We can now earn £1,000 in interest without paying tax, with interest above that taxed at your usual income tax rate. Banks no longer take off 20% tax at source. If you earn over £1,000 in interest then you have to report that to the tax office or complete a tax return.
Britain doesn't have a problem with people hoarding money. People getting into debt is more of an issue so we need to encourage rather than discourage saving. Britain is a good country to save and invest as we have a generous ISA limit of £15,000 a year, soon to increase to £20,000. If that isn't enough, the capital gains tax exemption is £11,000 and in the unlikely event that you need to pay tax on your capital gains because you have exhausted both the ISA and capital gains limits, from this tax year the rate has been reduced to 10% for basic rate taxpayers.
