Savers paid into 9.7m cash Isas during the 2019-20 tax year, up from 8.5m the year before, according to the latest provisional savings data from HMRC.
Stocks and shares Isa subscriptions also increased by 300,000 to just over 2.7m, while the number of lifetime Isa savers more than doubled, from 223,000 in 2018-19 to 545,000 in 2019-20.
Here, Which? takes a closer look at the data to find out the UK's Isa savings trends.
The boost of around 1.2m new cash Isa subscriptions in 2019-20 suggests that this kind of account has regained favour with savers.
However, such popularity may be short-lived. As the is counted as a cash Isa product, it may be that the 2019-20 surge is due to prospective first-time buyers trying to get the account before it closed to new customers on 30 November 2019. If this is the case, we may find that cash Isa subscriptions reduced in 2020-21.
Savers paid in more than £48.7bn into their cash Isas in 2019-20, averaging at a little over £5,000 savings per person.
Elsewhere, stocks and shares Isa subscriptions were also up in 2019-20 to reach over 2.7m, after subscriptions fell by more than 400,000 between 2017-18 and 2018-19. While fewer people saved into a stocks and shares Isa, on average those who did saved more, putting away £8,875 in 2019-20.
As for , these accounts seem to be dwindling, as 2019-20 saw subscriptions fall for the third year in a row to just 34,000. Launched in April 2016, these kinds of accounts had stricter rules imposed on them by the Financial Conduct Authority in 2019, instructing peer-to-peer platforms to protect less experienced investors.
That being said, those who choose to invest in these products continue to save more money than ever. In 2019-20, £438m was saved into IFISAs, an average of nearly £12,900 per account.
Junior Isas have seen a steady growth in popularity since they were introduced in 2011, but 2019-20 is the first time the children's savings product saw more than 1m subscriptions.
These were made up of just over 700,000 Junior cash Isas, and over 300,000 Junior stocks and shares Isas.
Despite the Junior Isa allowance being raised to £9,000 in 2019-20, up from £4, 368 in 2018-19, the amount being saved doesn't seem to have jumped accordingly. In 2019-20, £971m was deposited, £3m less than in 2018-19 - this is mainly down to a fall in the amount being saved into Junior stocks and shares Isas, which fell by £45m in a year.
The Junior Isa's predecessor, Child Trust Funds (CTFs), has a very different story. In 2019-20, more than 5.1m CTFs had no money paid into them at all, and almost 5.3m had a value of £2,499 or less.
HMRC has previously revealed that more than 700,000 CTFs are dormant, meaning no action has been taken on the fund since they were first set up.
HMRC had opened 1.8m CTFs after parents of eligible children hadn't made a choice about whether or not they wanted one, and it's thought that many more account details have been lost in the years since the accounts were first opened.
Launched as an alternative to Help to Buy Isas in April 2017, the lifetime Isa has had a relatively slow start - but the pace appears to be picking up.
In 2019-20, 545,000 savers paid into one of these accounts, up from 223,000 the year before, but they're not saving quite as much on average. In 2019-20, nearly £1.25bn was paid into lifetime Isas, giving an average of just over £2,300 per person - in 2018-19 lifetime Isa savers were depositing an average of just over £2,700.
While it's worth noting that savers can only deposit up to £4,000 per year into a lifetime Isa, these averages are still nowhere near this amount.
Everyone in the UK receives an Isa allowance: £20,000 in 2021-22 for adults, and £9,000 for children in . These allowances were both the same in 2020-21, and describe the maximum amount you're allowed to deposit in this tax year.
The £20,000 adult allowance can all be used on one account, or split between several - as long as they are different types of Isas, ie you can't pay into more than one of the same type of Isa in the same tax year.
If you exceed your allowance, HMRC may tell your provider to remove extra money from your account and you may be charged tax on the interest the over-subscription earned.
While having such a rigid savings limit might be frustrating, Isas come with the important benefit of being free from tax, regardless of how much interest you earn.
Child trust funds (CTFs) are tax-free savings accounts for children born between 1 September 2002 and 2 January 2011 and are closed to new savers.
They were introduced as a way to encourage children to practice long-term saving, while also giving every child a financial boost when they reached 18. The government made a contribution of £250 to £500 to each fund, which could be added to by parents and grandparents.
The accounts closed to new savers in January 2011 due to the introduction of Junior Isas, and it's now possible to transfer CTFs to a Junior Isa.
Children can control the management of the account when they turn 16, but cannot withdraw the money until they turn 18.