Don't let tax sneak a bite of your savings.
Choose a fixed rate ISA and protect your savings interest from tax.
Lock in a fixed rate for your Cash ISA
A Fixed Rate Cash ISA gives you certainty about the tax-free interest you'll earn.
So make the most of your hard-earned savings. Choose a fixed rate and relax in the knowledge your money is working hard; and earning tax-free interest.
Lock in for 12 months with our 1 Year Fixed Rate Cash ISA.
If you want to fix your rate for longer, explore our full range of ISAs including fixed rate options for 2, 3, or 5 years.
3.70%
Tax-free^ / AER† (Fixed)
1 Year Fixed Rate Cash ISA
- Open with £500
- Save up to £20,000 this tax year
- No withdrawals allowed
- Choose interest paid yearly or monthly
- Pay into the account whilst it's on sale
Transfer your ISA to Principality
Fancy moving your Cash ISA to us? Excellent. We can't wait to have you on board.
We'll help you make the most of your tax-free savings options.
Follow our simple transfer process and find out why over 500,000 savers choose Principality Building Society.
Your ISA questions answered
An ISA can suit people looking for a tax-efficient way to save (because with an ISA you don't pay any tax on the interest you earn).
This can be particularly relevant if you're a higher or additional rate tax payer.
Before choosing an ISA it might help to work out whether you're eligible to pay tax on your savings.
Depending on the ISA you open, there may be a limit on how many withdrawals you can make.
Make sure you check the account terms to understand any withdrawal limits.
'Flexible ISAs' let you withdraw money and replace it before the end of the same tax year, without it affecting your annual ISA allowance.
Our fixed rate ISAs aren't flexible. Which means they don't allow withdrawals. You could choose to close the ISA or transfer the balance to a different ISA; but you may lose out on interest.
Withdrawing funds from an ISA could mean you lose out on interest you could have earned if your money was in the account. It can also impact your tax advantages.
Each tax year (from April 6 until April 5 the next year) you have an annual tax-free ISA allowance.
The ISA allowance for the 2025/2026 tax year is £20,000. For people under the age of 65, this amount is set to reduce to £12,000 from the 2027/28 tax year.
You can split your allowance across different types of ISAs (cash ISAs, stocks & shares ISAs, lifetime ISAs, and innovative finance ISAs). But you can only pay into one cash ISA each tax year,
Different cash ISAs have different terms. Some allow you to pay in the full amount of your annual cash ISA allowance as a lump sum. With others you can pay in smaller amounts over time.
For more detail read our latest guide on the latest ISA rules and allowances.
If you don’t use your full tax-free ISA allowance by April 5, you’ll lose it when the tax year ends.
In short, you can’t carry this year’s ISA allowance over into next year.
Make the most of your tax-free savings by using your full ISA allowance. Remember you can save up to £20,000 this tax year.
If you already have a Principality ISA, we're here to help you maximise your tax-free benefits.
Contact your local branch or log in to your online profile to pay into your ISA.
ISA help and guides
- ISAs
Learn how to choose the right cash ISA and use your tax-free allowance.
4 mins
- ISAs
Learn about tax-free savings, different ISA types, and how to choose the right one for your needs.
3 mins
- ISAs
Make the most of your ISA allowance with this guide.
3 mins
Why choose Principality?
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Our branch promise
We're on Welsh high streets to stay. We're real people who promise clear guidance, no pressure and support at every stage of your savings journey.
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Owned by you
We're run for our members. Decisions are made for your benefit and your voice helps shape what we do.
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Your savings protected
Your eligible deposits with Principality Building Society are protected up to £120,000 under the Financial Services Compensation Scheme.
Compare all Cash ISAs
Browse our full range of Cash ISAs including all our fixed rate and variable rate options.
*Gross interest is the rate of interest before income tax is deducted at the rate set by law.
†AER stands for Annual Equivalent Rate and illustrates what the interest rate would be if interest was paid and compounded once each year.
^Tax-free means the interest you earn isn't subject to UK Income Tax and Capital Gains Tax. Tax treatment depends on your individual circumstances and could change in future.