ISA vs Pension: How Does the Tax Treatment Differ?
The two are taxed at different points. gov.uk describes tax relief on money paid into a pension, and says you pay tax when you take money out of a pension. For an ISA, it says you do not pay tax on interest, income or capital gains inside the account, and you can take money out at any time without losing tax benefits. In the 2026-27 tax year the overall ISA allowance is £20,000; this guide describes differences and does not say which suits anyone.
The site's rules data was last checked against gov.uk on 26 September 2026. Figures typed in this guide may not yet reflect a later change, and the descriptions of gov.uk pages are summaries that may also lag. The current figures are on the ISA rules at a glance page. General information only, not financial advice.
How is money paid into an ISA taxed?
The GOV.UK page on how ISAs work says that every tax year you can save up to £20,000 in one account or split the allowance across multiple accounts. It says the tax year runs from 6 April to 5 April. The page read does not describe any tax relief on money paid into an ISA, and this guide does not state that there is one. The comparison below therefore treats an ISA payment as a plain payment into an account, with the tax treatment described where gov.uk describes it: on interest, income and gains while the money is held.
The allowance is shared across the ISAs a person pays into. gov.uk says, for example, that you can only pay into one Lifetime ISA in a tax year, and that the Lifetime ISA limit counts towards the overall limit (GOV.UK Lifetime ISA guide). The Lifetime ISA also has a government bonus, covered on the Lifetime ISA calculator page.
How is money paid into a pension taxed?
The GOV.UK page on tax on your private pension says your private pension contributions are tax-free up to certain limits, and that you usually pay tax if the savings in your pension pots go above those limits. It names a yearly cap, the annual allowance, and links to a separate guide on it. This guide does not type that figure, because the page that names it is a summary and the figure can change; read it on gov.uk.
The GOV.UK page on pension tax relief says relief is given on contributions up to a level tied to your annual earnings, and that where you have no earnings, relief applies up to a set amount for the tax year. It says HMRC can ask you to repay relief on amounts above the earnings limit. The same page describes two ways relief arrives:
- automatically, where your employer deducts workplace pension contributions from your pay before Income Tax, or where your provider claims basic-rate relief from the government and adds it to your pot ("relief at source");
- by your own claim, which gov.uk says you may need to make if you pay Income Tax above the basic rate, if your scheme is not set up for automatic relief, or if someone else pays into your pension. You can usually claim through Self Assessment or the online claim service.
It also says you cannot claim relief if the scheme is not registered with HMRC. The GOV.UK page on personal pensions says the same about registration and adds that you usually get tax relief on money you pay into a pension.
What is the tax while the money is held?
For an ISA, gov.uk says you do not pay tax on the interest on cash in an ISA, or on the income or capital gains from investments in an ISA, and that you do not need to declare any ISA interest, income or capital gains on a tax return (how ISAs work). For how that compares with a savings account outside an ISA, see is ISA interest taxable?
For a pension, the pages read do not say how growth inside the pension is taxed. The pages on tax on your private pension and on pension tax relief cover contributions and withdrawals, and the other pension pages read do not cover growth. This guide therefore says nothing about it. Check the GOV.UK pages on tax on your private pension for any change.
What is the tax when money is taken out?
The GOV.UK page on withdrawing your money from an ISA says you can take your money out of an ISA at any time, without losing any tax benefits. It says to check your ISA's terms for any withdrawal rules or charges. It also says that if your ISA is flexible, you can take out cash and put it back in the same tax year without reducing that year's allowance, and that there are different rules for taking money out of a Lifetime ISA. A Lifetime ISA's withdrawal charge is described in our worked examples.
For a pension, the GOV.UK page on tax on your private pension says you pay tax when you take money out of a pension. The GOV.UK page on tax on a pension lump sum says you can take some of the money tax-free, that you pay Income Tax on any part of a lump sum above the lump sum allowance (or the lump sum and death benefit allowance), and that you may pay Income Tax at a higher rate if you take a large amount from a private pension. That page does not give the tax-free share as a figure, so this guide does not either.
Who can pay in?
For an ISA, the GOV.UK page on who can open an ISA says you must be 18 or over and either resident in the UK or a member of the armed forces or a Crown servant (or their spouse or civil partner) living abroad. A Lifetime ISA has an extra age condition: you must be under 40 to open one, and payments stop at 50. gov.uk says you cannot hold an ISA with someone else. Our guide on how to open an ISA covers the conditions in more detail.
For a pension, the pages read describe several routes rather than one set of conditions. The GOV.UK page on personal pensions says you can make regular or individual lump sum payments to a pension provider. The GOV.UK page on workplace pensions says a percentage of your pay is put into the scheme automatically every payday, that in most cases your employer also adds money, and that you may also get tax relief from the government. The relief page says relief may need claiming if someone else pays into your pension. The pages read do not set an age or residency condition for paying into a pension.
What are the allowances?
The table summarises what the pages read say, and where they are silent.
| Point | ISA | Pension |
|---|---|---|
| Yearly limit on paying in | £20,000 across all ISAs in the 2026-27 tax year | An annual allowance, named on gov.uk; relief is tied to annual earnings |
| Tax relief on payments in | The page read does not describe any | Described: automatic or by claim |
| Tax on interest, income and gains while held | None, per gov.uk | The pages read do not say |
| Tax on taking money out | No loss of tax benefits, per gov.uk | Tax is paid when money is taken out; some can be taken tax-free |
| When money can be taken out | At any time (Lifetime ISA has different rules) | The pages read do not say |
To see how a payment pattern would fit within it, the site's ISA calculator shows the arithmetic.
When can money be taken out?
For an ISA, gov.uk says at any time, without losing tax benefits. For a pension, the pages read do not say at what age money can be taken out. The early retirement page read covers only the State Pension, and the pension pages above point to other pages for how you can take your pension. So this guide does not state a minimum age. Read the relevant gov.uk pages, or ask the pension provider.
The two products are often discussed together in retirement writing. Our guide to ISA planning for retirement looks at how ISAs and pensions differ, and the site's learn page on allowances and rules explains the ISA limits.
What to check
- For an ISA: is the account an ISA, and does its own terms allow withdrawals and put-backs (is it flexible)?
- For a pension: is the scheme registered with HMRC, and is relief given automatically or does it need claiming?
- Which allowance figures apply in the current tax year, and where are they published?
- For a workplace pension: what does the employer pay in, and how are contributions taken from pay?
- For taking money from a pension: what does the provider say about age, tax-free amounts and tax?
- Is any of the tax treatment described on gov.uk due to change, and does the page carry a date?
Frequently asked questions
Is tax paid on interest inside an ISA?
gov.uk says you do not pay tax on the interest on cash in an ISA, or on income or capital gains from investments in an ISA. You do not need to declare ISA interest, income or gains on a tax return.
Does a pension get tax relief when money goes in?
The GOV.UK pension tax relief page says relief applies to contributions up to a level tied to your annual earnings, and describes automatic relief and relief you claim. It does not say that relief applies to ISA payments.
Do I pay tax on money taken out of a pension?
gov.uk says you pay tax when you take money out of a pension. It also says you can take some of it tax-free, and that Income Tax applies to a lump sum above the lump sum allowance.
Can an employer pay into an ISA as it can into a workplace pension?
The pages read say a workplace pension takes a percentage of pay automatically and that in most cases your employer also adds money. The ISA pages read do not mention employer payments, so this guide does not state a rule on that.
This guide does not constitute financial advice. Your personal situation, tax position, and savings goals may mean different strategies are appropriate. Consider speaking to a regulated financial adviser if you are uncertain.
