Fixed Rate Cash ISA
Put it away, know what you’ll earn. Tax-free and fixed.
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Compare our Cash ISAs
Want tax-free interest and a guaranteed return? Check our Fixed Rate Cash ISA terms and see how they compare with our flexible Instant Access option.
Helpful tip!
AER stands for Annual Equivalent Rate and illustrates what the interest rate would be if interest was paid and compounded each year. This allows you to compare easily what return you can expect from your savings over time. Tax-free means interest is exempt from UK Income Tax under current HMRC ISA rules. Tax treatment depends on individual circumstances and may change in the future.
Why choose a Cash ISA?
Our Fixed Rate Cash ISA gives you a tax-free guaranteed return, making it ideal for longer term savings goals.
Save up to £20,000 this tax year. You can move over any Cash ISAs you’ve got elsewhere too.
No changes no surprises, you will get a fixed rate for the full term and you have 14 days to fund your account.
You’ll earn daily and we’ll pay it in every month, tax free.
You can open multiple Cash ISAs, split your £20k allowance between fixed-rate and instant-access accounts to match your goals.
From opening to managing, it’s all sorted in our secure app.
Got questions? Chat, call or email our team when you need us.
Know your ISA allowance
Each tax year, you can deposit up to £20,000 across all your ISAs. With a Fixed Rate Cash ISA, once you’ve funded your account and your 14 day window closes, you can't top it up further, so plan your deposit carefully.
Bring your ISA balance with you
Already have an ISA elsewhere? No problem. We make it easy to digitally transfer in your existing ISA savings, whether it’s from this tax year or previous years. You can also hold accounts with multiple providers at the same time.
Reinvest your funds when your term ends
Your ISA will unlock at the end of its term and you’ll get 14 days to choose what to do next. Reinvest into a new Fixed Rate or Instant Access Cash ISA, transfer to another provider, or withdraw to your linked account.
You're in safe hands
We’re a fully regulated UK bank so you can rest easy knowing that your money is protected, up to £85,000 by the Financial Services Compensation Scheme (FSCS), the UK’s deposit guarantee scheme.
That's enough from us, hear it from those who matter
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Got a question?
We’ve got answers! Explore our most common savings questions, or head to our full FAQ page to find more.
Part of your deposits help fund greener choices for others — like home energy upgrades, low emission vehicle, and solar panels. In 2024, Tandem customers helped save over 70,000 tonnes of CO₂, the equivalent of taking 15,000 petrol cars off the road for a year.
Yes. Tandem is a fully regulated UK bank. Your savings are protected up to £85,000 by the Financial Services Compensation Scheme (FSCS).
You’ll have a 14-day window to decide whether to reinvest, move into an Instant Access ISA, withdraw, or transfer to another provider. If we don’t hear from you, your funds move into a Matured Funds Cash ISA at a variable rate so they keep earning interest tax-free
Yes. You can hold up to 20 Tandem ISAs (Instant Access or Fixed Rate), so you can separate savings goals or take advantage of new rates.
Interest is calculated daily and paid monthly, tax-free.
Yes. Simply start the process with your new provider and they’ll contact us. Transfers normally process with 4-5 working days, but can sometimes take up to 15 working days. If you’re in a Fixed Rate ISA, an early withdrawal charge will apply.
Yes. You can transfer an ISA from another provider without it affecting your allowance. Just open a Tandem Cash ISA and start the transfer in the app.
Yes, both our Instant Access and Fixed Rate Cash ISAs are flexible. That means you can withdraw and replace money in the same tax year without eating into your allowance. For example, if you deposit £20,000 but withdraw £5,000, you can still replace that £5,000 within the same tax year without exceeding your £20,000 limit.
Instant Access: withdraw and replace freely.
Fixed Rate: you can withdraw, but an early withdrawal penalty applies.
No – all interest earned in your ISA is completely tax-free and doesn’t use up your allowance.
Yes. You can now subscribe to more than one ISA of the same type in the same tax year (since April 2024). Just make sure your combined contributions don’t go over the annual £20,000 limit.
You can save up to £20,000 each tax year across all your ISAs (not just with Tandem). The overall amount a customer can hold across their Cash ISAs is £250,000.
Instant Access Cash ISA – variable tax-free rate, dip into your savings anytime.
Fixed Rate Cash ISA – fixed rate, with funds locked in for a fixed term. Great for long-term saving with a guaranteed return.
Both are FSCS-protected up to £85,000.
A Cash ISA (Individual Savings Account) lets you earn interest without paying tax on it. For the 2024/25 tax year, which runs from 6 April 2024 to 5 April 2025, you can save up to £20,000 across all your ISAs, tax-free.
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