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Established in Newport in 1869 to help local people build homes, we now help people across Wales and England buy properties and save for their future.
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Instant Access Savings Account 

Looking for an instant access savings account you can top up and dip into when you need to? 

This account can help you build savings for your future plans, whether that’s home improvements, making overpayments, or moving to your next home.

Issue 1

Interest Rate AER / Gross - Variable : 3.50%

Minimum: £100 

Maximum Balance: £25,000 (Sole Accounts) £50,000 (Joint Accounts)

Open your account : Online, in Branch or Agency

You must be:

  • An Existing Monmouthshire Building Society Residential Mortgage Account Holder
  • At least 18 years old
  • A UK resident (excluding Northern Ireland).

May be suitable for you if: 

green_tick You would like the ability to have instant access to your funds.  

green_tick You would like to make additional deposits to your savings.  

green_tick You would like to open and manage this account online and/or in person from Monmouthshire Building Society Branches.

Not suitable for you if:

red_cross You would like a fixed rate of interest on your savings.

red_cross You want to open this account over the phone, by post or the App. 

Additional Information:

  • If the balance goes below the minimum, you will receive an interest rate of 0.00% AER/Gross until the balance has been returned to the £100 minimum.

Click below to expand the Mortgage Customer Saver Summary Box and Terms and Conditions.

What is the interest rate?
  • 3.50% AER/Gross
  • This account tracks 0.25% below the Bank of England base rate (currently 3.75%).
  • Interest is calculated daily and paid once a year after 31 March.
Can Monmouthshire Building Society change the interest rate?
  • Yes, the interest rate is variable, which means the rate can go up or down subject to any changes to the Bank of England base rate.
  • We’ll update the interest rate within 14 business days whenever the bank rate changes.
What would the estimated balance after 12 months based on a £1,000 deposit?
  • £1,035.00
  • Based on £1,000 being paid into the account, the interest rate doesn’t change and there is no other money into or out of the account over 12 months.
How do I open and manage my account?

Who can open

  • You must be aged 18 or over and a UK resident (excluding Northern Ireland).
  • You must be an Existing Monmouthshire Building Society Residential Mortgage account holder.
  • This account is limited to one per customer. This can be sole or joint.

How to open

  • Online
  • Branch or agency

Minimum

  • The minimum balance is £100.
  • If the balance goes below the minimum, you will receive an interest rate of 0.00% AER/Gross until the minimum balance has been restored.

Maximum

  • You can pay money into your account up to the maximum balance £25,000 (Sole) / £50,000 (Joint).
  • The maximum that a member can invest with Monmouthshire Building Society across all accounts is £2,000,000.

How to manage

  • Online (my accounts for existing users), in branch or agency or via the MonBS app.
  • You can pay money into your account whenever you want, up to the maximum balance.
Can I withdraw money?
  • Yes, you can make withdrawals from your account without giving notice or incurring a penalty.
Additional Information
  • The gross rate means before tax.
  • You only pay tax on savings above your Personal Savings Allowance. Visit www.hmrc.gov.uk for more information.
  • AER is the Annual Equivalent Rate and shows what the rate would be if interest was paid and added on each year.
  • Rates and information correct from the 23 February 2026.

The information provided in the summary box is a summary of the key features of the Mortgage Customer Saver and is not intended to be a substitute for reading the terms and conditions above that apply to the account.

Next Steps

If you have read and understood all the information provided, and you would like to apply for a Mortgage Customer Saver simply click below.

Alternatively, you can visit one of our branches or agencies in person. 

Apply Online

 

FAQs

A Mortgage Customer Saver is a variable-rate savings account for Existing Residential account holders that lets you pay in and withdraw whenever you like without notice.

You must be 18 or over and a UK resident (excluding Northern Ireland). You must be an Existing MonBS Residential Mortgage account holder. The Mortgage Customer saver can be opened in sole or joint names.

You can open the Mortgage Customer Saver online, or in a MonBS branch or agency. (Telephone or postal opening isn’t available for this account.) You can manage the Mortgage Customer Saver online, on our App or in a MonBS branch or agency.

Yes. Mortgage Customer Saver allows unlimited, penalty-free withdrawals without notice, as long as the £100 minimum balance is maintained.

Yes. Eligible deposits in our Mortgage Customer Saver are protected by the Financial Services Compensation Scheme (FSCS) up to £120,000 per person. This gives our building society savers peace of mind that their money is protected.

For an Mortgage Customer Saver, Interest is shown as AER (Annual Equivalent Rate) which describes what the interest rate would be if interest was paid and compounded once each year, so you can compare accounts fairly.

Yes - by design, a Mortgage Customer Saver is ideal for short-term goals and rainy-day funds because you can withdraw at any time without notice.

If you need rate certainty and no access to your money for a certain period of time, a fixed-rate bond or ISA may suit you better. Choose the Mortgage Customer Saver if flexibility and access are your priorities.

The Mortgage Customer Saver has a minimum balance of £100 and a maximum balance of £25,000 (Sole Accounts) / £50,000 (Joint Accounts). You can add funds whenever you like and make unlimited withdrawals.

FSCS Protected