Revealed: where the richest savers live
Savers in Harrow in London and Kirkwall in Scotland typically have the highest Isa balances in the country, according to data based on amounts held with Britain's biggest building society.
Nationwide, which analysed how much money people have saved into its accounts, said that Harrow and Kirkwall are the only areas of the UK where its savers have an average Isa balance of more than £15,000.
The average balance in Harrow is £15,476 and the typical amount put aside in Kirkwall is £15,442.
People living in London and the surrounding commuter belt as well as those in Scotland dominated the list, with Bromley, Ilford, Kingston-upon-Thames, Edinburgh, Dumfries and Galloway, St Albans and Hemel Hempstead featuring highly.
Protect your savings from the taxman: compare ISAs
At the other end of the spectrum, Nationwide found that the lowest balances can also be found in London. Savers with the east London postcode of E have the lowest average Isa balance at £10,182.
People in Cardiff and Newport in South Wales were also found to have some of the lowest Isa balances in the UK, with Leeds, Manchester, Blackburn, Truro and Bradford also on the low balances list.
Earlier this week, figures from the British Bankers' Association (BBA) showed that people saved 57% more into their Isas last year than they did in 2013, with £13.1 billion placed in the tax-free accounts in 2014. New rules introduced last July gave people a more generous and a more flexible Isa allowance.
The annual Isa allowance is currently set at £15,000. All of this can be saved, tax-free, in cash, or all in stocks and shares, or any combination of the two. The annual limit will increase when the new tax year starts in April.
Protect your savings from the taxman: compare ISAs
Richard Napier, Nationwide's divisional director of savings, said: "According to our own internal data, it is savers in Greater London, the South East and Scotland that are really making the most of their Isa allowance, with the average Isa balance in these regions higher than anywhere else in the UK.
"With the annual allowance increasing to £15,240 in April, we would hope to see those average balances increase over the next 12 months."
Protect your savings from the taxman: compare ISAs
Here are the 20 UK postal areas with the highest average Isa balances among Nationwide's customers, with the postal area and town or city followed by the typical balance held:
1. HA, Harrow, £15,476
2. KW, Kirkwall, £15,442
3. BR, Bromley, £14,443
4. IG, Ilford, £14,039
5. KT, Kingston-upon-Thames, £13,828
6. EH, Edinburgh, £13,678
7. DG, Dumfries and Galloway, £13,617
8. AL, St Albans, £13,549
9. PH, Perth, £13,520
10. TW, Twickenham, £13,437
11. AB, Aberdeen, £13,410
12. SL, Slough, £13,169
13. WD, Watford, £13,165
14. BH, Bournemouth, £13,074
15. HP, Hemel Hempstead, £13,055
16. KY, Kirkaldy, £12,984
17. TD, Galashiels, £12,980
18. SM, Sutton, £12,978
19. CA, Carlisle, £12,966
20. DT, Dorchester, £12,860
And here are the 20 UK postal areas with the lowest average Isa balances among Nationwide's customers, with the postal area and town or city followed by the typical balance held:
1. E, East London, £10,182
2. SE, South East London, £10,192
3. CF, Cardiff, £10,403
4. NP, Newport, £10,448
5. ME, Rochester, £10,472
6. LS, Leeds, £10,597
7. NN, Northampton, £10,612
8. M, Manchester, £10,700
9. TR, Truro, £11,078
10. BB, Blackburn, £11,112
11. B, Birmingham, £11,124
12. NG, Nottingham, £11,129
13. HX, Halifax, £11,170
14. SN, Swindon, £11,173
15. PL, Plymouth, £11,231
16. ML, Motherwell, £11,270
17. HU, Hull, £11,273
18. MK, Milton Keynes, £11,276
19. CT, Canterbury, £11,318
20. BD, Bradford, £11,348
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