Savings & Investing
Should I Use a Cash ISA or Savings Account? — Tax-Free Threshold Check
Compare Cash ISAs and regular savings accounts. When the Personal Savings Allowance makes an ISA unnecessary, and when a Cash ISA still saves you tax.
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.
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 £85,000 |
Up to £85,000 |
| 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 |
£32,486 |
£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 |