The first £1000 of any savings interest isn't subject to income tax, so, assuming a 1.5% interest rate, You'd need more than £65,000(ish) in savings before an ISA was worth bothering with. Put more simpy, if the best interest rate you can get is 1% you'll need over £100,000 in savings before the tax advantage of an ISA comes into play. Then you'll only gain if the ISA interest rate is above 0.8%. It's all a bloody silly game isn't it? One thing's for certain - the bankers aren't getting any poorer.