How to find the best cash Isa What is an Isa?

Cash Isa savings bank

Saving in a cash Isa means you won't have to pay tax on the interest you earn

Isas are tax-free savings or investment accounts offered by banks, insurers, asset managers, building societies and National Savings & Investments (NS&I). 

There are two main types of Isa - cash Isas and stocks and shares Isas. All interest earned on money held in a cash Isa is tax-free.

If you are a basic or higher-rate taxpayer, the interest you earn on savings will usually be taxed at 20% or 40% - so Best Rate cash Isas will often offer a better return than Best Rate savings accounts once tax is taken into consideration.

The Which? savings and Isa comparison tables let you search all available savings accounts and Isas from all available providers to choose the best savings rates based on quality of service as well as cost and benefits.

Go further: Which? savings and Isa comparison tables - compare the best deals on the market

What is a cash Isa?

A cash Isa is essentially the same as a traditional savings account, except there are limits on the amount of cash you can transfer in and there is no tax to pay on the interest you earn.

In the current tax year, you can place £15,000 into a cash Isa 

You must consider your individual circumstances before opening a cash Isa to make sure your chosen account is the best one for your needs. There are three principal types of cash Isa, explained below.

Instant access cash Isas

This type of Isa provides savers with the ability to pay in and withdraw money at any time throughout the tax year. 

Some let you pay in and withdraw any amount, while others will place annual limits on your withdrawals, or demand minimum deposits from customers.

One thing to remember is that instant access cash Isas often have variable rates of interest – the price you pay for the luxury of moving cash in and out of your account freely. 

If interest rates rise, you could see the value of your savings rise, too - but conversely, if interest rates drop, this could negatively affect the return you receive.

Which? Comparison Table: Best instant access cash Isas - all available deals compared

Fixed-rate cash Isas

If you’re looking to tie up your savings for a while, you might want to consider a fixed-rate cash Isa. These lock away your money for a set period, usually between one and five years, and in return pay you a higher interest rate. Generally, the longer you tie up your money, the better the interest rate you will receive.

It’s important to note that fixed-rate cash Isas do not allow you to withdraw your money at any time – you forgo the flexibility of easy access to your savings in return for a top rate. So, if you want to access your cash at any point, you may face a penalty, either in the form of a fixed fee or a reduction in your interest rate.

Fixed-rate cash Isas often require a lump sum investment rather than regular savings. If you want to maximise the tax efficiency of your Isa and are able to put a large chunk aside of cash in one go, this is your best option.

Which? Comparison Table: Best fixed-rate cash Isas - all available deals compared

Regular savings cash Isas

These cash Isas will pay a fixed rate of interest over a set period – usually a year – on the provision that you make a regular monthly savings contribution. 

This monthly deposit is limited to your savings allowance within the Isa. In the 2014/15 tax year, you can contribute a maximum of £1,250 per month without exceeding your total limit of £15,000.  

Again, it's likely you will not be able to withdraw any of your savings from a regular savings cash ISA, and pay face a penalty if you do so.

Which? Comparison Table - Best regular savings cash Isas - all available deals compared

What is a stocks and shares Isa?

In a stocks and shares Isa, all capital gains and income are protected from tax (although all dividends are still subject to 10% tax). You can learn more about how these accounts work in our guide titled stocks and shares Isas explained.  

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