Cash ISA

Harpenden Building Society Hart ISA Review

A competitive instant access cash ISA from Harpenden Building Society. It ranks 30th of 115 instant access cash ISAs we track.

Variable rate

3.86%AER

Rate checked Oct 2026Got this account? Leave a review

Protection

FSCS£120,000

Min balance

£1

Max balance

£250,000

Access

Instant

Interest paid

Annually

Transfers in

Accepted

How It Stacks Up

Ranks 30th of 115

Instant access cash ISAs we track

Above average
This account 3.86%
UK CPI (Aug 2026)
3.10%
Pays 0.76% more
Average instant access cash ISA
2.91%
Pays 0.95% more
Best instant access cash ISA
4.87%
Pays 1.01% less

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

A better-paying alternative

Trading 212 bank logo

Trading 212

Cash ISA

4.75%

AER

  • Pays 0.89% more than this Harpenden Building Society account
  • Includes a 1.15% bonus for 12 months, then 3.60%
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A Good Fit For

  • Pro: New and existing savers
  • Pro: Savers who want instant access

Worth Weighing Up

  • Con: The rate is variable, so it can go down

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Estimated returns with Harpenden Building Society's Cash ISA

What you could earn with Harpenden Building Society's Hart ISA.

Estimated interest

£1,000 saved

£38.60

At 3.86% AER

£5,000 saved

£193

At 3.86% AER

£10,000 saved

£386

At 3.86% AER

£250,000 saved

£9,650

At 3.86% 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 Harpenden Building Society Hart ISA

Jonny PeaseCo-Founder, DepositScout

The Harpenden Building Society Hart ISA pays 3.86%, which is below the cash ISA market average and 1.39% behind the category leader at 5.25%, so this is not a rate I would lead with for most savers. It does at least beat August 2026 CPI inflation of 3.1% by 0.76%, which keeps your money growing in real terms. The account suits someone who wants instant access, accepts transfers in, and is comfortable with a mutual building society, but I would still check whether the extra yield elsewhere is worth switching for.

Compare Cash ISAs

2 alternatives to Harpenden Building Society's Hart ISA

Same type of account, closest on rate.

Common questions about the Hart ISA

D

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