18 Month Fixed Rate Cash ISA (Issue 343)

Our 18 Month Fixed Rate Cash ISA may be right for you if you have a lump sum to invest and you can leave your investment untouched for 18 months.

  Summary Box Balance Tax-free^ AER†
Maturity Interest £500 plus 4.55% 4.50%
Monthly Interest £500 plus 4.41% 4.50%
  • Apply online, in branch or agency
  • Save from £500 to £20,000
  • Transfer in your existing ISA
  • Interest is calculated on your daily balance and paid on maturity or monthly
  • Additional deposits permitted while the ISA remains on sale
  • No withdrawals allowed before the end of the 18 month term
  • Closure permitted subject to loss of 150 days' interest
  • Limited availability
Summary Box
  Summary Box
What is the interest rate? Fixed annual interest      4.55% Tax-free^ each year     4.50% AER†
Fixed monthly interest    4.41% Tax-free^ each year     4.50% AER†

(See the meanings of ‘Tax-free’ and ‘AER’ at the bottom of the page)

Interest is calculated each day on the money in the account and paid:
  • at maturity, 18 months after the date your ISA is opened; or
  • monthly, starting one month after the date your ISA is opened, and then each month after that;
    whichever you choose.
  • Can Principality change the interest rate? No, the rate is fixed for 18 months until the ISA matures (when the account comes to an end).
    What would the estimated balance be after 18 months based on a £1,000 deposit? £1,068.25
    This is based on you choosing to have interest paid at maturity and added to your ISA, and not making any further payments into the account.
    How do I open and manage my account?
    • You must be a UK resident and satisfy the minimum age requirements to open a cash ISA (see your 18 Month Fixed Rate Cash ISA account terms).
    • You can open your ISA in branch, at an agency, or online. If you want to open this ISA with funds from a Principality Fixed Term ISA that has matured, you can do this online, in branch, agency, or by post.
    • You must keep at least £500 (the minimum balance) in the account.
    • You cannot pay in more than the ISA Allowance each tax year. The ISA Allowance for the current tax year 2024/2025 is £20,000. You can only pay your ISA Allowance into one Principality cash ISA in the current tax year.
    • You can transfer unlimited amounts from ISAs from previous tax years, as these are not part of your current year’s ISA allowance.
    • You must make the first payment into your ISA within five business days of it opening. If you don’t, we may close the account.
    • You can keep making payments into your ISA while we are still offering this ISA to customers.
    • Your ISA will mature 18 months after the date your ISA opened.
    • You can manage your ISA in branch, at an agency, by post, or by using the online service, Your Account as principality.co.uk.
    Can I withdraw money?
    • No, you cannot make withdrawals from your ISA before it matures.
    • If you close or transfer your ISA before the end of the fixed-rate term (within 18 months), you will lose 150 days’ interest. If you haven’t earned enough interest to cover the 150 days’ interest it will be taken from the money in the account. This means you may get back less than you originally put in.
    • We will write to you before your ISA matures to find out what you want to do with your money.
    • If we don't receive any instructions from you before your ISA matures, we will move your money to our Variable Rate Cash ISA or the nearest equivalent we offer at the time.
    Additional information
    • Service charges and costs may apply to your account. These are outlined in our Tariff of Charges.
    • In certain circumstances we may refuse an instruction for using an account. These circumstances are set out in our Savings Terms and Conditions.
    • The tax treatment of your savings depends on how individual circumstances and may change in the future. This is set by HM Revenue and Customs (HMRC). Further information can be found at gov.uk/individual-savings-accounts/how-isas-work
    • The interest rates quotes above were correct on 27/06/2024.

    Before you apply below, please read the 18 Month Fixed Rate Cash ISA Issue 343 Terms & Conditions

    If you are transferring previous years' ISA subscriptions, please enter your initial deposit as £500 on the application form. The application form will ask you whether you are making a transfer later in the process.

    You can only invest in one Principality Cash ISA per tax year.

    As you will be bound by the account terms and your information is held in accordance with our privacy policy, you should read, print and save the below documents for your records. If you have any queries relating to them please contact us for further information.

    Please also read the following:

    ^Tax-free means UK Income Tax and Capital Gains Tax is not deducted from the interest you earn. This depends on your individual circumstances, and may change in future.

    †AER stands for Annual Equivalent Rate and illustrates what the interest rate would be if interest were paid once each year on the whole balance, including previous interest payments. 

    • 6th largest UK building society
    • A mutual building society, owned by and run for the benefit of our 500,000 members
    • Over 150 years experience
    • Taking care of over £10 billion of our customers' assets

    We are covered by the FSCS

    Find out more about what it means for you.


    Product previously viewed

    have not viewed any products yet