ISA Returns on £4,000

Investing £4,000 in a UK ISA at 4.5% earns £985 tax-free over 5 years and £2,212 over 10 years. A basic rate taxpayer saves £0 in tax over 5 years compared to a standard savings account.

Investing £4,000 in an ISA at 4.5% earns £985 tax-free over 5 years (£2,212 over 10 years). At this level, a basic rate taxpayer may not exceed the £1,000 Personal Savings Allowance (PSA) even outside an ISA, but an ISA still protects you if rates rise or your savings grow — and it never hurts to start building your ISA pot early.

ISA returns on £4,000 over time

The table below shows how £4,000 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	£4,180	£180	£180	£0	£0
3 years	£4,565	£565	£565	£0	£0
5 years	£4,985	£985	£985	£0	£0
10 years	£6,212	£2,212	£2,212	£0	£0

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 £4,000 performs over 5 years at different rates (basic rate taxpayer):

Rate	ISA return	Non-ISA return	Tax saved
3.0%	£637	£637	£0
4.5%	£985	£985	£0
6.0%	£1,353	£1,353	£0
8.0%	£1,877	£1,877	£0

How to invest £4,000 in an ISA

£4,000 fits within the annual £20,000 ISA allowance, so you can invest the full amount in a single tax year. You have several options:

• Cash ISA — Fixed or easy-access savings accounts. Currently paying 4–5%. Best for money you may need within 1–3 years.
• Stocks & Shares ISA — Invest in funds, ETFs, or individual shares. Higher potential returns over 5+ years, but your capital is at risk.
• Split approach — Keep an emergency fund (3–6 months' expenses) in a Cash ISA and invest the rest in a Stocks & Shares ISA for long-term growth.

If you are aged 18–39 and saving for a first home or retirement, consider a Lifetime ISA (LISA): you get a 25% government bonus on contributions up to £4,000/year (£1,000 free per year). The LISA counts toward your £20,000 annual ISA allowance.

Compare ISA returns at other amounts

• £2,000: £492 tax-free over 5 years (£0 tax saved)
• £3,000: £739 tax-free over 5 years (£0 tax saved)
• £5,000: £1,231 tax-free over 5 years (£0 tax saved)
• £6,000: £1,477 tax-free over 5 years (£0 tax saved)

Frequently asked questions

How much will £4,000 earn in an ISA?

At 4.5%, £4,000 earns £985 tax-free over 5 years, growing to £4,985. Over 10 years, it grows to £6,212 (£2,212 return).

How much tax do I save with an ISA on £4,000?

Over 5 years at 4.5%, a basic rate taxpayer saves £0 and a higher rate taxpayer saves £0. Over 10 years, savings increase to £0 (basic) and £0 (higher).

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.