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For the 2025-26 tax year, everyone has an Isa allowance of £20,000 – this is the maximum amount you're allowed to pay into Isas between 6 April 2025 and 5 April 2026. This Isa allowance is unchanged from 2024-25.
However, from April 2027 the amount under-65s can pay into cash Isas will be cut to £12,000 a year (though the overall £20,000 limit will continue to apply across all types of Isa).
If you don't use your annual Isa allowance before the end of each tax year, you'll lose it - and it will start anew on 6 April.
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Savers can deposit the full £20,000 into a cash, stocks and shares or innovative finance Isa, or any mix of the three types.
If you're saving up to buy property, there is also the Help to Buy Isa (no longer open to new applicants) and, for those aged 18-40, the lifetime Isa. Both of these Isas have lower annual limits - but, whatever you pay in will be taken from your £20,000 allowance.
The graph below shows the maximum amount you can pay into each type of Isa within one tax year, up to a total of £20,000.
All UK residents aged 18 or over can have a cash Isa or a stocks and shares Isa.
Crown employees serving overseas or individuals married to such employees are also eligible to open Isas.
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Compare and chooseIsa rules aren't just about how much you pay in; some accounts are flexible, meaning that you can withdraw money from an Isa account and replace it, without the replacement counting further towards your Isa allowance.
The only condition is that you top up your Isa in the same tax year the withdrawal was made.
If you put it back in the next year, it will count towards your new annual allowance. This also applies to cash held in a stocks and shares Isa and Innovative Finance Isa, but not Junior Isas or lifetime Isas.
But there are a few extra caveats, depending on when the money in the Isa was saved.
There's no specific limit for how many Isas you can hold overall and you can now pay into multiple Isas of the same type in the same tax year.
There are limits on some types of Isa, however.
You can have several cash Isas, stocks and shares Isas, innovative finance Isas and lifetime Isas, and only pay into one each year - but you can only have one Help to Buy Isa at a time.
You can now pay into more than one type of Isa in the same tax year.
This means you can make new deposits into multiple cash Isas (A Help to Buy Isa counts as a cash Isa option), stocks and shares Isas, innovative finance Isas and lifetime Isas.
If you've paid into, say, a cash Isa and see a better rate on the market, you may be able to take advantage of it by transferring your Isa savings to the new provider (note that not all Isas accept transfers - so check before you apply).
You are also now able to transfer part of your account balance from one Isa provider to another, rather than being forced to transfer the lot (as was the case in previous tax years). This means you can keep some funds with your existing provider and retain that account if you wish.
Help to Buy Isas closed to new savers on 30 November 2019, but people with existing Help to Buy Isas can continue to save into them.
If you're saving up for a property deposit you receive a £50 bonus for every £200 saved in the Isa. There is a maximum government bonus of £3,000 on £12,000 of savings.
You can open your Help to Buy Isa with a one-off deposit of £1,000 to kick things off, and then add £200 per month thereafter.
This means that in the first year of opening a Help to Buy Isa you can save up to £3,400, and then £2,400 each year afterwards.
The lifetime Isa is for adults aged 18-39 only, designed to help them buy their first home or save for retirement.
You can pay in up to £4,000 in each tax year, and the government will add a £1 bonus for every £4 you save - so, that's a bonus of up to £1,000 a year. You can only add savings up to the age of 50.
Find out more in our guide to best lifetime Isas.
In the 2025-26 tax year, the annual limit for contributions to Junior Isas is £9,000 (unchanged from the 2024-25 tax year).
Parents and guardians can pay into Junior Isas up to the limit - what they pay in does not come out of their own Isa allowance, as the Junior Isa belongs to the child.
Once the child turns 18, the Junior Isa account will be changed to an adult Isa, and the individual can decide on what they want to do with the money.
Junior Isas are not eligible for new rules on flexible withdrawals.
Find out more in our guide to the best Junior cash Isas.
If you're married or in a civil partnership, your spouse can inherit the Isa allowance you've built up through saving into these tax-free accounts - regardless of whether they actually inherit the money in your Isas.
They will get an additional Isa allowance equivalent to your Isa savings Isa at the time of your death, and is referred to as an 'additional permitted subscription', or APS allowance.
The rules are quite complex, so we'd advise reading our guide on Isa inheritance.
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Because it's possible to have several Isas with different providers, there is a risk that you might pay in too much during a single tax year.
At the end of the tax year, records for individuals will be checked, so HMRC will know that you've paid in too much money. You may be let off with a warning letter if it's the first time this has happened but it's best to check yourself.
Where HMRC decides to take action, your Isa provider may be instructed to remove over-subscriptions and tax any income or growth related to that money.
HMRC advises against trying to correct the mistake by drawing money out - you can call its Isa helpline instead on 0300 200 3300.