For those who’ve taken advantage of tax-efficient investing over the years, it’s important to periodically review your ISA portfolio to make sure it’s working best for you.

Old ISAs can be earning some of the worst rates around. And just because one type of ISA might have suited you well a few years ago, it might not be what’s right for you now.

What’s more, if you have lots of different ISA pots, you could make better returns by consolidating them into one single pot – and you’ll only have to pay one provider.

This is where transferring your ISAs can come in useful – allowing you to move your old tax-free investments to other providers that offer a risk appetite and rate that best suit your current circumstances, without losing the all-important tax wrapper.

So, here’s our overview of some the key questions we get asked about ISA transfers.

How much can I transfer?

There are no restrictions on how much you’re able to transfer. And, importantly, the ISA allowance (currently £20,000 for the 2018/19 tax year) only applies to new money invested in this tax year.

So, even if you have more than £20,000 in an ISA (and those who have used their ISA wrapper to full effect for a number of years will), you can still transfer it all across and have your full annual allowance to play with.

How does an ISA transfer work?

First things first: don’t just withdraw the money from one ISA and put it in another! Doing so means the money loses its tax-free ISA status – and so reinvesting it will count towards your annual allowance.

Instead, to transfer an ISA, you need to instruct your old provider to send the money directly to your new provider.

Whatever you do, if you want to make an ISA transfer, make sure you do it by the proper routes.

Do I have to transfer a whole ISA in one go?

No – it’s up to you. You can transfer an entire ISA, or instruct what’s called a ‘partial transfer’ and just move some of it. But note that not all ISA providers allow partial transfers – so make sure you check first.

What type of ISAs can I transfer into?

You can transfer your ISA money between cash, stocks & shares, and Innovative Finance ISAs. And, providing it’s from a previous tax year and your old provider allows partial transfers, there are no restrictions on how you can split it, or which type of ISA you can transfer into.

How much does an ISA transfer cost?

In many cases, nothing. Octopus Choice, for example, won’t charge you a penny for making an ISA transfer. But there may be exit charges, so you should check with your existing provider before deciding what to do.

One of the most common reasons for being charged would be if you are transferring from a fixed-term ISA that has yet to come to the end of its term.

How does an ISA transfer affect my ISA allowance?

It doesn’t. As above, only new money invested in this tax year will affect your ISA allowance.

How long does an ISA transfer take?

This can depend on the provider and type of ISA, but it shouldn’t take longer than around two to four weeks.

In our experience, a transfer into an Octopus Choice ISA usually completes in around a fortnight.

Can I transfer my current tax year’s subscriptions?

You can transfer money from the current tax year, however you’re only allowed to transfer the full amount.

Sounds arduous. How much paperwork does it take?

Not as much as you might think. You simply need to fill out an ISA transfer form (which, in our case, we’ll pre-populate for you based on a few short bits of info that you can fill out online), then sign and send it to your existing provider. Then it’s up to the two ISA providers to make the arrangements.

How can I transfer my existing ISA into an Octopus Choice ISA?

We’ve done all we can to make it as easy as possible. Once you’ve created an ISA account, you’ll see the option to transfer an existing ISA from your dashboard. You’ll be prompted to fill in a few details, then download the ISA transfer form and cover letter which we’ll have pre-populated with all the relevant details. You then simply need to sign it, and send it to your current provider. We’ll then arrange the transfer with them.

Note that you’ll need to have opened an Octopus Choice ISA in order to be able to make an ISA transfer. This should only take a few minutes.

Of course, remember that because investments are concentrated in loans secured against property, they could be affected by market conditions. And for the same reason, instant access to your money can't be guaranteed. You should know that the value of an investment can fall as well as rise, and you may not get back the full amount you invest.

Also, the Octopus Choice ISA isn't a flexible ISA. Any withdrawals that you make from this year's money will still count towards your ISA allowance. Tax treatment is subject to change and depends on individual circumstances.