Savings and investment information is for educational purposes only. The value of investments can go down as well as up. Cash savings up to £85,000 per person per institution are protected by the FSCS.
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With the Personal Savings Allowance giving most people some tax-free interest anyway, many wonder if Cash ISAs are still worth using. Here’s how to decide.
Read more: See our Isas guide for a complete overview of this topic.
Cash ISA vs Savings Account — Key Differences
Feature
Cash ISA
Savings Account
Tax on interest
Always tax-free
Taxed above PSA
Annual contribution limit
£20,000
No limit
Interest rates
Often slightly lower
Often slightly higher
Multiple accounts
Yes (since 2024)
Yes
FSCS protection
Up to £120,000
Up to £120,000
Transfers
Between ISA providers
N/A
Counts toward PSA
No
Yes
The Personal Savings Allowance Explained
Tax band
Annual income
PSA (tax-free interest)
Basic rate
Up to £50,270
£1,000
Higher rate
£50,271 – £125,140
£500
Additional rate
Over £125,140
£0
When You’d Exceed Your PSA
At current interest rates (~4-5%), here’s roughly how much savings would breach the PSA:
Tax band
PSA
At 4% interest
At 5% interest
Basic rate
£1,000
~£25,000
~£20,000
Higher rate
£500
~£12,500
~£10,000
Additional rate
£0
Any savings
Any savings
Decision Guide by Tax Band
Basic-Rate Taxpayer (£1,000 PSA)
Savings level
Best option
Why
Under £20,000
Best-rate savings account
PSA covers all interest; higher rates available
£20,000 – £40,000
Start using Cash ISA
Approaching PSA limit
Over £40,000
Cash ISA essential
Definitely exceeding PSA
Higher-Rate Taxpayer (£500 PSA)
Savings level
Best option
Why
Under £10,000
Either works
PSA covers most interest
£10,000 – £20,000
Cash ISA recommended
Will exceed £500 PSA
Over £20,000
Cash ISA essential
Significant tax savings
Additional-Rate Taxpayer (£0 PSA)
Use a Cash ISA for all your savings. Every penny of interest in a regular account is taxable at 45%.
The Long-Term ISA Advantage
Even if you don’t need an ISA now, building your ISA pot has compounding benefits:
Year
ISA balance (£10k/year, 4%)
Tax saved vs savings account (higher rate)
1
£10,400
£80
3
£32,465
£540
5
£56,330
£1,253
10
£124,864
£4,994
20
£309,692
£16,194
The ISA wrapper becomes more valuable as your pot grows.
When a Regular Savings Account Wins
Situation
Why savings account
Small savings (under PSA threshold)
Higher interest rates available
Short-term savings
No need for ISA wrapper
Already maxed ISA allowance
Can’t put more in ISAs
Need a regular saver account
Best rates often in non-ISA products
Fixed-rate needed
Non-ISA fixed rates often higher
When a Cash ISA Wins
Situation
Why Cash ISA
Higher or additional-rate taxpayer
Low or zero PSA
Large savings pot
Exceeds PSA
Long-term saver
Compounding tax-free benefit
Income near tax band boundary
Interest could push you into higher band
Planning for retirement
Tax-free accessibility at any age
The Best Strategy — Use Both
Account
Purpose
Easy-access savings account
Day-to-day buffer, regular saver deals
Cash ISA
Long-term savings, emergency fund
Fixed-rate savings
Known goals with specific timeline
Fixed-rate Cash ISA
Best of both — tax-free and higher rate
Common Myths
Myth
Reality
“ISAs are pointless now”
Only true for small savers on basic rate
“ISA rates are always worse”
Gap has narrowed; sometimes ISAs match
“I can’t have multiple Cash ISAs”
You can since April 2024
“ISA money is locked away”
Easy-access Cash ISAs let you withdraw anytime
“I lose my ISA allowance if I withdraw”
Flexible ISAs let you replace withdrawals in the same tax year