I refer the hon. Member to the written answer I gave on 26 November 2008, Official Report, column 2028W.
Although the capital limits that apply when calculating tariff income are kept under continual review they can be increased only when priorities and resources allow. The tariff income rules are not intended to represent any rate of return that could be obtained from investing capital. They provide a simple method of calculating the weekly contribution that people with capital in excess of £6,000 (or £10,000 if in a care home) are expected to make from those resources to help meet their normal living expenses. As there is no link with actual market rates, deductions remained unaltered throughout the period of rising interest rates, just as they have done more recently, when interest rates have been lower.