Since April 6 last year savers have been able to open an unlimited number of Isas. You can even hold multiple versions of the same type with the same provider. 

The only restriction is that you can’t exceed your £20,000 annual allowance, and you can hold only one Lifetime Isa (Lisa).

So what is the ideal approach and how can you decide what is right for you?

Consider one of each type

Each Isa serves a particular financial need, as explained on the front page of this pullout.

Cash Isas, for example, work well for savings you may need to withdraw quickly in an emergency, while stocks and shares Isas come with a higher risk but have far more potential to grow your money over the long term.

Junior Isas (Jisas), meanwhile, allow you to save up to £9,000 a year for a child, and Lisas are a great tool for saving up a deposit for your first home or for retirement.

Malvee Vaja, a financial adviser at Rathbones Financial Planning, says: ‘Multiple Isas may make sense when you are trying to save for multiple things at the same time.

‘For example, you might have a different pot for your short-term, medium-term and long-term needs, with different investment strategies for each one.’

Several of the same type

The case for opening multiple Isas of the same type is perhaps strongest for cash Isas.

This strategy enables you to keep some in an easy-access version where you can get to it in an emergency, and the rest in a fixed-term account where

it will earn a guaranteed rate of interest for a specified time.

Holding several fixed-rate Isas can also be helpful if you have some cash that you can afford to lock away for a few years and some you may need sooner.

This approach really comes into its own when interest rates are rising, because you can store some of your savings and then add more if an even better rate comes along.

Anna Bowes, a leading savings expert from financial advisers The Private Office, says: ‘If you are expecting to come into some extra cash later in the tax year, you could open an Isa immediately with whatever you have now and still be able to use the remainder of your allowance at a later date.’

Of course, just because the rules have changed doesn’t mean that all savings providers have adopted them.

Bowes adds: ‘While most now allow you to open another cash Isa, even if you’ve already funded one with a different provider in the same tax year, this doesn’t necessarily mean they allow multiple cash Isas under one roof.’

Those that allow savers to divide their money across the multiple Isas they offer include Aldermore, Close Brothers Savings, Skipton Building Society and TSB.

Mix and match within an Isa

Some providers make it easy to hold multiple products within the same Isa wrapper.

For example, Zopa’s Smart Isa comes in two types – Access and Fixed Term. You can mix and match up to 20 of them to spread your savings in whichever way you like.

Other providers, such as Monzo, also allow hybrid Isas where you can open a cash Isa alongside a stocks and shares one.

That said, if you’re after the best rates for both fixed and easy-access Isas, chances are they won’t be from the same provider.

Bowes says: ‘It’s worth picking the best rates available rather than worrying about whether one provider allows multiple Isas in the same tax year.’

Others point to the difficulties of juggling multiple statements, which can make it harder to track how your savings are performing.

One could prove all you need

The case for taking out multiple stocks and shares Isas within a tax year is less obvious, given many providers offer access to a wide range of different investments within the Isa wrapper already.

It might, though, be useful if you want to access a specific investment or product feature that’s not available with your current provider.

You might want to try out an Isa provider that you’re not too sure about, perhaps one of the no-commission share trading platforms such as eToro or Trading 212.

Or one with a good app – investment website Boring Money reports that some of the newer players, such as Lightyear, Saxo Invest, Trading 212 and XTB, might appeal to more seasoned investors.

If you’re building a large Isa portfolio, it might also feel like time to diversify your platform risk by holding your money in more than one.

Investment platforms have to hold their customers’ assets separately to their own.

This means your investments would be returned to you in the event of a platform’s failure.

However, there is still the risk that a firm going bust would take a few months to pay out, and you may not be able to trade in the interim.

Beware of duplicate fees

Charlene Young, pensions and savings expert at investing platform AJ Bell, says: ‘If you’re buying the same share in two different investment Isas, you’ll be paying two dealing charges rather than just one if they were consolidated.’

Vaja points out that some Isa providers offer a discount on charges as you save more.

In this case, you may be better off using just one account to benefit from lower fees. Over the long-term, fees can make a significant difference to investment returns.

In the end, your ideal Isa complexity may depend on the time and energy you have for financial affairs.

So it’s probably your ability to keep an eye on all your accounts that will determine the number of Isas you open.

Charlotte Ransom, chief executive at advice firm Netwealth, says: ‘It’s good that savers can now have more than one Isa, but less can be more – my rule is to keep things simple and streamlined wherever possible.’