5 year fixed rate ISAs are ideal for longer term savers who are looking to secure a guaranteed interest rate on their tax free savings rather than having to rate chase.

The longer term means that banks offer better interest rates than are generally available on any other type of cash ISA - so opting for a 5 year cash ISA could help you to secure the best tax free returns possible with a cash-based account.

Banks do this as an incentive for savers to forgo access to their money for this length of time, as withdrawals are not generally permitted during the 5 year fixed rate term.

5 year fixed rate ISA withdrawals

However, while a guaranteed return on your savings for 5 years does seem like an attractive proposition you do need to consider whether there is any chance you will need access to your money during that time.

Most 5 year fixed rate ISAs lock your money in for 60 months and as such do not allow early closure or withdrawals.

This not only presents issue if you need to draw on your savings, but also prevents you from moving your money to a more profitable home if the interest rates available elsewhere rise.

If there is a substantial increase in interest rates in the years after you open your ISA, you will be losing out on potential earnings for the next four or three years respectively - even if you opted for the best fixed rate ISA over 5 years you could find at the time.

Some ISA providers do allow withdrawals during the account term but will apply a penalty of as much as 365 days interest, lowering your return considerably.

Interest rates offered

Your first point of comparison of the best 5 year ISA deals ought to be the interest rate they pay. A fixed rate ISA paying a higher interest rate means more money for you at the end of the 5 years.

However, some of the best 5 year fixed rate cash ISAs do advertise tiered interest rates, reserving the highest returns for savers with high level deposits. As such, when you carry out your 5 year ISA comparison you need to restrict your search to accounts that pay a high interest rate on the amount of money you have to save.

You'll also need to make sure you can fulfil the minimum deposit criteria - this can vary between 1 and 15,000 depending on the account - and find out whether you're able to transfer previous years' ISA allowances into the account (should this be something you want to do).

You can find all the 5 year fixed rate ISAs best rates and compare their features in our 5 year fixed rate ISA comparison table.

Remember that banks automatically move funds in 5 year fixed rate ISAs to accounts that pay significantly lower interest rates at the end of the fixed rate term.

To ensure that your savings remain profitable you need to make a note to move the funds to a new fixed rate ISA if you want to continue enjoying the high rates.