NS&I vs Cash ISA vs Savings Account — Where to Put Your Cash
How NS&I savings, Cash ISAs, and standard savings accounts compare on interest rates, tax, access, and safety. UK comparison guide for 2026.
·5 min read
With Cash ISAs, NS&I products, and high-interest savings accounts all competing for your money, choosing where to save depends on how much you have, your tax rate, and what you need.
Quick Comparison
Feature
NS&I (Premium Bonds)
Cash ISA
Savings Account
Interest/return
Prize fund rate ~4.00% (variable)
4.0%–5.0% (best rates)
4.0%–5.2% (best rates)
Tax treatment
Tax-free (prizes)
Tax-free (interest)
Taxable (but PSA applies)
FSCS protection
No — HM Treasury backed (100%, unlimited)
Yes (£85,000 per banking group)
Yes (£85,000 per banking group)
Access
Instant (usually 3–5 working days)
Instant or fixed term
Instant or fixed term
Annual allowance
N/A (max £50,000 holding)
£20,000 per tax year
No limit
Guaranteed return
No — prizes are random
Yes (if fixed rate)
Yes (if fixed rate)
Minimum deposit
£25
£1 (varies by provider)
£1 (varies by provider)
The Personal Savings Allowance (PSA)
Before choosing, understand how much savings interest you can earn tax-free.
Tax band
PSA (tax-free savings interest)
Approx. savings to exceed PSA at 4.5%
Basic rate (20%)
£1,000
~£22,000
Higher rate (40%)
£500
~£11,000
Additional rate (45%)
£0
Any interest is taxable
If your total savings interest stays within the PSA, you pay no tax in a standard savings account. A Cash ISA provides no additional tax benefit in this case — just pick the highest rate.
When Each Option Wins
NS&I Premium Bonds — Best When:
Situation
Why
You have over £85,000 in savings
HM Treasury backing has no upper limit — safer than FSCS
You are an additional rate taxpayer
No PSA — Premium Bond prizes are tax-free
You are a higher rate taxpayer with PSA used
Tax-free prizes avoid further tax
You enjoy the lottery element
Chance of £1 million prize (very small odds)
You want a safe place to park cash
Zero risk of loss
Cash ISA — Best When:
Situation
Why
You are a higher or additional rate taxpayer with savings above PSA
All interest is permanently tax-free
You want to build a long-term tax-free pot
ISA allowance carries over year to year
You are saving for a specific goal over multiple years
Tax-free compounding
Cash ISA rate matches or beats savings accounts
No downside vs savings account
Savings Account — Best When:
Situation
Why
You are a basic rate taxpayer with under ~£22,000 in savings
PSA covers your interest — ISA not needed
The best savings rate is significantly higher than the best Cash ISA rate
More money > tax shelter
You want a fixed-term bond with a high rate
Fixed savings accounts often pay more than fixed Cash ISAs
You need instant access to a large emergency fund
Easy access savings accounts are flexible
Rate Comparison (Illustrative — Check Current Rates)
Product type
Easy access
1-year fixed
2-year fixed
Best savings account
4.5–5.0% AER
4.5–5.0% AER
4.2–4.8% AER
Best Cash ISA
4.3–4.8% AER
4.3–4.8% AER
4.0–4.5% AER
NS&I Premium Bonds
~4.0% average (prizes)
N/A
N/A
NS&I Income Bonds
~4.0%
N/A
N/A
NS&I Direct Saver
~3.5%
N/A
N/A
Savings accounts often pay slightly higher rates than equivalent Cash ISAs because they rely on the PSA for tax efficiency rather than ISA wrapper.
Tax Comparison — How Much You Keep
Basic Rate Taxpayer with £20,000 Savings
Product
Gross interest (4.5%)
Tax
Net interest
Savings account
£900
£0 (within £1,000 PSA)
£900
Cash ISA
£900
£0 (ISA tax-free)
£900
Premium Bonds (~4%)
~£800 (average prizes)
£0 (tax-free)
~£800
At this level, savings account and Cash ISA are equivalent. Premium Bonds return less.
Higher Rate Taxpayer with £50,000 Savings
Product
Gross interest (4.5%)
Tax
Net interest
Savings account
£2,250
£700 (£2,250 – £500 PSA = £1,750 × 40%)
£1,550
Cash ISA (£20k) + savings (£30k)
£900 (ISA) + £1,350 (savings)
£340 (£1,350 – £500 PSA = £850 × 40%)
£1,910
Premium Bonds (£50k max)
~£2,000 (average prizes)
£0
~£2,000
At this level, Premium Bonds and Cash ISA provide meaningful tax savings.
Additional Rate Taxpayer with £50,000 Savings
Product
Gross interest (4.5%)
Tax
Net interest
Savings account
£2,250
£1,012 (£2,250 × 45%)
£1,238
Cash ISA (£20k) + savings (£30k)
£900 (ISA) + £1,350 (savings)
£608 (£1,350 × 45%)
£1,643
Premium Bonds (£50k max)
~£2,000 (average prizes)
£0
~£2,000
For additional rate taxpayers, Premium Bonds and Cash ISAs are significantly better.
NS&I Product Range
Product
Rate (approx.)
Access
Tax treatment
Min/Max
Premium Bonds
~4.0% (prize fund rate)
Instant (3–5 days)
Tax-free
£25 / £50,000
Income Bonds
~4.0% (variable)
Instant
Taxable (but uses PSA)
£500 / £1m
Direct Saver
~3.5% (variable)
Instant
Taxable (but uses PSA)
£1 / £2m
Green Savings Bonds
~3.5–4.0% (fixed 3 years)
Fixed term
Taxable
£100 / £100,000
Guaranteed Growth/Income Bonds
~4.0% (fixed 1 year)
Fixed term (penalty for early withdrawal)
Taxable
£500 / £1m
Where to Put Savings — Decision Tree
Your situation
Best option
Basic rate, savings under £20,000
Whichever pays the highest rate (savings account or Cash ISA)
Basic rate, savings over £22,000
Use Cash ISA allowance first, then best savings account
Higher rate, savings under £11,000
Whichever pays the highest rate
Higher rate, savings over £11,000
Cash ISA + Premium Bonds + savings account (in that order)
Additional rate, any amount
Cash ISA (£20,000) + Premium Bonds (up to £50,000) + NS&I/savings for the rest
Over £85,000 total savings
Spread across banking groups for FSCS cover, or use NS&I (unlimited Treasury backing)