ISA Returns on £40,000

Investing £40,000 in a UK ISA at 4.5% earns £9,847 tax-free over 5 years and £22,119 over 10 years. A basic rate taxpayer saves £953 in tax over 5 years compared to a standard savings account.

With £40,000 in ISAs, you earn £9,847 tax-free over 5 years at 4.5%. Note: the annual ISA allowance is £20,000, so you would need to build up this balance over 2 tax years. A basic rate taxpayer saves £953 in tax over 5 years, while a higher rate taxpayer saves £2,837.

ISA returns on £40,000 over time

The table below shows how £40,000 grows in an ISA at 4.5% versus a taxable account, for a basic rate (20%) and higher rate (40%) taxpayer.

Period	ISA value	ISA return	Non-ISA return (basic)	Tax saved (basic)	Tax saved (higher)
1 year	£41,800	£1,800	£1,640	£160	£520
3 years	£45,647	£5,647	£5,099	£525	£1,630
5 years	£49,847	£9,847	£8,812	£953	£2,837
10 years	£62,119	£22,119	£19,329	£2,332	£6,315

Returns assume compound growth at 4.5% per year. Non-ISA accounts deduct tax annually on interest above the PSA.

How the interest rate affects your ISA advantage

Higher rates mean more interest, more tax, and a bigger ISA advantage. Here is how £40,000 performs over 5 years at different rates (basic rate taxpayer):

Rate	ISA return	Non-ISA return	Tax saved
3.0%	£6,371	£6,085	£271
4.5%	£9,847	£8,812	£953
6.0%	£13,529	£11,668	£1,667
8.0%	£18,773	£15,683	£2,671

Building £40,000 in ISAs

The annual ISA allowance is £20,000, so reaching a £40,000 ISA balance takes at least 2 tax years of maximum contributions (excluding growth). Here is a suggested approach:

• Maximise each year — Contribute £20,000 before 5 April each tax year
• Invest early — Contributing at the start of the tax year gives more time for compound growth
• Consider your mix — Cash ISAs for short-term needs, Stocks & Shares ISAs for long-term growth
• Transfer old ISAs — You can transfer previous years' ISAs between providers without affecting this year's allowance

Compare ISA returns at other amounts

• £35,000: £8,616 tax-free over 5 years (£711 tax saved)
• £38,000: £9,355 tax-free over 5 years (£856 tax saved)
• £42,000: £10,340 tax-free over 5 years (£1,050 tax saved)
• £45,000: £11,078 tax-free over 5 years (£1,195 tax saved)

Frequently asked questions

How much will £40,000 earn in an ISA?

At 4.5%, £40,000 earns £9,847 tax-free over 5 years, growing to £49,847. Over 10 years, it grows to £62,119 (£22,119 return).

How much tax do I save with an ISA on £40,000?

Over 5 years at 4.5%, a basic rate taxpayer saves £953 and a higher rate taxpayer saves £2,837. Over 10 years, savings increase to £2,332 (basic) and £6,315 (higher).

Can I put £40,000 in an ISA in one year?

No. The annual ISA allowance is £20,000. You would need 2 tax years to shelter £40,000 in ISAs. However, you can transfer ISAs from previous years between providers without affecting your current allowance.

Cash ISA or Stocks & Shares ISA?

Cash ISAs are lower risk and suit savings you may need within 1–3 years. Stocks & Shares ISAs have higher potential returns over 5+ years but your capital is at risk. Many people use both — cash for near-term needs and investments for long-term growth.