People who are most likely to take full advantage of their tax-free savings allowance are those living in London and the South East, according to research.
Halifax said that people living in the capital and in the South East make up nearly three-quarters of the top 30 local authorities in which people have the most saved in a cash ISA.
But those with the highest average ISA balances are those who live in the Derbyshire Dales. They have on average £10,478 put away in the tax free savings product, which is 34% above the UK average of £7,836.
People in Brentwood in Essex, East Dorset, Chiltern in Buckinghamshire, Harrow and South Bucks have also saved an average of more than £10,000 in ISAs.
But at the other end of the spectrum, cash ISA savings levels are lowest in the London Boroughs of Hackney and Southwark, where people have set aside only around £4,760 and £5,260 each respectively into the accounts.
Savers in Glasgow and West Lothian, both in Scotland, have the next lowest amount set aside in an ISA at £5,294 and £5,346 respectively.
Overall, 13 of the top 30 local authorities with the highest average levels of ISA savings are in London, while nine are in the South East and four are in the East Midlands.