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.
Contents
Choosing between cash and stocks depends on your timeline and risk tolerance.
Read more: See our Isas guide for a complete overview of this topic.
Quick Comparison
Feature
Cash ISA
Stocks & Shares ISA
Returns
Fixed interest
Variable growth
Risk
None (capital safe)
Value can fall
Best for
Short-term (0-5 years)
Long-term (5+ years)
Typical returns
4-5%
5-10% average*
Complexity
Simple
More complex
*Historical long-term average, not guaranteed
How They Work
Cash ISA
How It Works
Details
You deposit money
Into savings account
Bank pays interest
At advertised rate
Interest is tax-free
In ISA wrapper
Capital protected
FSCS up to £120,000
Stocks & Shares ISA
How It Works
Details
You deposit money
Into investment account
Buy investments
Shares, funds, bonds
Value changes
Based on markets
Gains/dividends tax-free
In ISA wrapper
Capital at risk
Can lose money
Risk and Returns
Historical Returns
Timeframe
Cash (Example)
Stocks (Example)
1 year
4-5%
-20% to +30%
5 years
15-25% total
0% to +60%
10 years
30-50% total
50-150%
20 years
50-100% total
150-400%
Note: Stocks figures are illustrative ranges, not guarantees
Risk Explained
Risk Type
Cash
Stocks
Capital loss
None
Yes
Inflation risk
Yes (if rate below)
Less long-term
Volatility
None
High short-term
Inflation Consideration
Scenario
Impact
Cash ISA pays 4%
Inflation is 5%
Real return
-1%
Your money
Loses purchasing power
When to Choose Cash ISA
Ideal For
Situation
Why Cash
Emergency fund
Need certainty
Saving for 0-5 years
Can’t wait out dips
House deposit (near-term)
Need the full amount
Risk averse
Sleep at night
Money you can’t lose
Guaranteed balance
Cash ISA Examples
Goal
Timeline
Recommendation
Emergency fund
Ongoing
Cash ISA
Holiday in 2 years
Short
Cash ISA
Car in 3 years
Short
Cash ISA
Wedding next year
Short
Cash ISA
When to Choose Stocks & Shares
Ideal For
Situation
Why Stocks
5+ year timeline
Time to recover dips
Retirement saving
Decades to grow
Beating inflation
Higher potential
Can accept volatility
Not checking daily
Wealth building
Long-term growth
Stocks & Shares Examples
Goal
Timeline
Recommendation
Retirement in 20 years
Long
Stocks & Shares
Child’s university (13 years)
Long
Stocks & Shares
Financial freedom
Long
Stocks & Shares
House deposit (short term)
Short
Cash instead
The Effect of Time
£10,000 Over 20 Years
Scenario
Cash (3% avg)
Stocks (7% avg)
Year 5
£11,593
£14,026
Year 10
£13,439
£19,672
Year 15
£15,580
£27,590
Year 20
£18,061
£38,697
Difference
+£20,636
Note: Illustrative only, returns not guaranteed
Why Time Matters for Stocks
Timeframe
Likelihood of Loss*
1 year
~25%
5 years
~10%
10 years
~3%
20 years
~0.1%
*Based on historical global stock market data
Using Both
Recommended Split
Purpose
ISA Type
Emergency fund
Cash
Short-term goals
Cash
Medium-term (5-10 years)
Mix
Long-term (10+ years)
Stocks & Shares
Example Allocation
Total ISA: £20,000
Split
Emergency fund
£5,000 Cash
Holiday saving
£3,000 Cash
Retirement
£12,000 Stocks
As You Approach Goal
Years to Goal
Stock Allocation
10+ years
80-100%
5-10 years
50-80%
3-5 years
20-50%
0-3 years
0-20%
Types of Investments (S&S ISA)
Options Within S&S ISA
Investment
Risk Level
Individual shares
Highest
Active funds
Higher
Index funds/ETFs
Moderate
Bonds
Lower
Mixed (multi-asset)
Varies
For Beginners
Good Starting Points
Why
Global index fund
Diversified
Target date fund
Auto-adjusts
Multi-asset fund
Balanced
Costs
Cash ISA
Cost
Typical
Account fee
Usually £0
Transaction costs
£0
All you lose
Some potential return
Stocks & Shares ISA
Cost
Typical
Platform fee
0-0.45%
Fund fees
0.1-1.5%
Trading fees
£0-12 per trade
Total
0.2-2% per year
Common Platform Fees
Platform
Annual Fee
Notes
Vanguard
0.15% (capped £375)
Best for fund-only investors
Fidelity
0.35%
Broad fund choice
AJ Bell
0.25%
Shares and funds
Hargreaves Lansdown
0.45%
Wide range, high quality tools
Trading 212
0% platform fee
Earns on spreads
Impact of Fees
On £10,000 Over 20 Years
Low Fees (0.3%)
High Fees (1.5%)
Assuming 7% returns
£35,236
£26,533
Lost to fees
£3,461
£12,164
Common Questions
Can I Transfer Between ISA Types?
Transfer Direction
Allowed?
Cash ISA → S&S ISA
Yes
S&S ISA → Cash ISA
Yes
Previous years’ ISAs
Yes
Current year ISA
Yes — follow official transfer process
Important: Never withdraw money and redeposit into a different ISA type. You will lose that portion of your annual allowance permanently. Always use the official ISA transfer process through your new provider.
Should I Avoid Stocks When the Market Is High?
No. Time in the market consistently beats timing the market:
Strategy
Long-Term Outcome
Invest immediately, every year
Usually the best result
Wait for a crash before investing
Often misses significant growth
Regular monthly investing (drip-feed)
Smooths volatility, reduces anxiety
What If the Market Crashes Soon After I Invest?
Response
Likely Outcome
Panic and sell
Locks in the loss permanently
Hold and wait
Most major markets have historically recovered
Continue investing or buy more
Often benefits most from the recovery
If you have 10+ years, a crash is a buying opportunity rather than a disaster. If you need the money within 5 years, it shouldn’t be in stocks in the first place.