What interest rate does the Castle Trust Bank 3 year Fixed Rate e-Cash ISA pay?

The Castle Trust Bank 3 year Fixed Rate e-Cash ISA pays 5.05% AER fixed.

How much interest could I earn?

Saving £10,000 for 3 years would earn about £1,593 at 5.05% 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 three-year cash ISAs?

At 5.05% AER it ranks 2nd of 28 three-year cash ISAs we track. The best pays 5.11% and the average is 4.61%.

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Cash ISA

Castle Trust Bank 3 year Fixed Rate e-Cash ISA Review

One of the best-paying three-year cash ISAs, from Castle Trust Bank, with a £1,000 minimum deposit. It ranks 2nd of 28 three-year cash ISAs we track.

Rate checked Oct 2026Got this account? Leave a review

Fixed rate · 3 years

5.05%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 2nd of 28

3-year cash ISAs we track

Among the best

This account 5.05%

UK CPI (Aug 2026): 3.10%; Pays 1.95% more
Average 3-year cash ISA: 4.61%; Pays 0.44% more
Best 3-year cash ISA: 5.11%; Pays 0.06% less

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

Compare cash ISAs

A Good Fit For

Pro: New and existing savers

Worth Weighing Up

Con: Your money is locked in for 3 years
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 3 year Fixed Rate e-Cash ISA.

Estimated interest

£1,000 saved

£159

At 5.05% AER

£5,000 saved

£796

At 5.05% AER

£10,000 saved

£1,593

At 5.05% AER

£500,000 saved

£79,640

At 5.05% AER

Estimated over the 36-month term, 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 3 year Fixed Rate e-Cash ISA

Jan WatermannCo-Founder, DepositScout

Castle Trust Bank's 3 Year Fixed Rate e-Cash ISA pays 5.05%, which sits above the cash ISA market average but 0.07% behind the current market leader at 5.12%. At 1.95% above August 2026 CPI of 3.1%, the real return is genuinely positive, which matters over a three-year commitment. The main catch is that there is no access until maturity, so this suits savers who are confident they will not need the money for the full three years. You need at least £1,000 to open it, and ISA transfers in are accepted.

Compare Cash ISAs