What interest rate does the Castle Trust Bank 1 year Fixed Rate e-Cash ISA pay?

The Castle Trust Bank 1 year Fixed Rate e-Cash ISA pays 4.92% AER fixed.

How much interest could I earn?

Saving £10,000 for 1 year would earn about £492 at 4.92% AER. This assumes the rate stays the same and interest stays in the account.

How much can I pay in?

You can deposit at least £1,000 and up to £500,000.

Can I withdraw my money?

No. Withdrawals aren't allowed until the account matures.

When is interest paid?

Interest is paid at the end of the term.

Who can open this account?

New and existing Castle Trust Bank customers can open it. You can open it online or in the app.

Is my money protected?

Yes. Eligible deposits are protected by the Financial Services Compensation Scheme (FSCS) up to £120,000 per person, per banking licence.

Can I transfer an existing ISA in?

Yes, transfers in from other ISAs are accepted.

How does it compare with other one-year cash ISAs?

At 4.92% AER it ranks 1st of 47 one-year cash ISAs we track. The best pays 4.92% and the average is 4.37%.

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Cash ISA

Castle Trust Bank 1 year Fixed Rate e-Cash ISA Review

A top-paying one-year cash ISA from Castle Trust Bank, with a £1,000 minimum deposit. None of the other 46 one-year cash ISAs we track pays more.

Rate checked Oct 2026Got this account? Leave a review

Fixed rate · 1 year

4.92%AER

Rate checked Oct 2026Got this account? Leave a review

Protection

FSCS£120,000

Min balance

£1,000

Max balance

£500,000

Access

At maturity only

Interest paid

On Maturity

Transfers in

Accepted

How It Stacks Up

Ranks 1st of 47

1-year cash ISAs we track

Top rate

This account 4.92%

UK CPI (Aug 2026): 3.10%; Pays 1.82% more
Average 1-year cash ISA: 4.37%; Pays 0.55% more
Best 1-year cash ISA: 4.92%; About the same

Inflation: ONS. Averages and best rates: accounts on DepositScout.

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A Good Fit For

Pro: New and existing savers

Worth Weighing Up

Con: Your money is locked in for 1 year
Con: You need at least £1,000 to open it
Con: Not flexible: money you withdraw can't be replaced without using more allowance

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Estimated returns with Castle Trust Bank's Cash ISA

What you could earn with Castle Trust Bank's 1 year Fixed Rate e-Cash ISA.

Estimated interest

£1,000 saved

£49.20

At 4.92% AER

£5,000 saved

£246

At 4.92% AER

£10,000 saved

£492

At 4.92% AER

£500,000 saved

£24,600

At 4.92% AER

Estimated over one year, if the rate stays the same and interest is left in. Amounts outside the account's minimum or maximum aren't shown.

Our Expert Opinion on Castle Trust Bank 1 year Fixed Rate e-Cash ISA

Jan WatermannCo-Founder, DepositScout

Castle Trust Bank's 1 Year Fixed Rate e-Cash ISA pays 4.92%, which sits above the cash ISA market average but 0.20% behind the category leader at 5.12%, so it is solid without being the best available. At 1.82% above August 2026 CPI of 3.1%, your money does at least grow in real terms. The account accepts ISA transfers in and suits savers who want a straightforward fixed ISA with a £1,000 minimum, though the one genuine catch is that your money is completely locked away until maturity, with charges if you need it sooner.

Compare Cash ISAs