Cash ISA

Monmouthshire Building Society 1 Year Fixed Rate Cash ISA Review

A one-year cash ISA from Monmouthshire Building Society, with a £1,000 minimum deposit. It ranks 42nd of 47 one-year cash ISAs we track.

Fixed rate · 1 year

3.90%AER

Rate checked Oct 2026Got this account? Leave a review

Protection

FSCS£120,000

Min balance

£1,000

Max balance

£20,000

Access

At maturity only

Interest paid

Annually

How It Stacks Up

Ranks 42nd of 47

1-year cash ISAs we track

Below average
This account 3.90%
UK CPI (Aug 2026)
3.10%
Pays 0.80% more
Average 1-year cash ISA
4.37%
Pays 0.47% less
Best 1-year cash ISA
4.92%
Pays 1.02% less

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

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Worth Weighing Up

  • Con: Your money is locked in for 1 year
  • Con: You need at least £1,000 to open it

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Estimated returns with Monmouthshire Building Society's Cash ISA

What you could earn with Monmouthshire Building Society's 1 Year Fixed Rate Cash ISA.

Estimated interest

£1,000 saved

£39.00

At 3.9% AER

£5,000 saved

£195

At 3.9% AER

£10,000 saved

£390

At 3.9% AER

£20,000 saved

£780

At 3.9% 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 Monmouthshire Building Society 1 Year Fixed Rate Cash ISA

Jan WatermannCo-Founder, DepositScout

Monmouthshire Building Society's 1 Year Fixed Rate Cash ISA pays 3.90%, which is below the market average for cash ISAs and 1.22% behind the category leader at 5.12%, so I would not call this rate particularly strong. It does at least beat August 2026 CPI inflation of 3.1% by 0.80%, which means your money is growing in real terms. The key catch is that access is locked until maturity, with deposits capped at £20,000 and a minimum of £1,000. If you want something slightly better without fixing, Tembo or XTB both offer cash ISAs at 4.00%.

Compare Cash ISAs

2 alternatives to Monmouthshire Building Society's 1 Year Fixed Rate Cash ISA

Same type of account, closest on rate.

Common questions about the 1 Year Fixed Rate Cash ISA

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