£12,570. It’s the most important number in UK personal finance that most people can’t explain — the amount you can earn each year before paying a penny of Income Tax. But the personal allowance isn’t just a tax threshold; it’s the keystone that determines how your savings are taxed, how much of your ISA allowance you really need, and whether that “tax-free” savings account is actually saving you any tax at all. Here’s what the personal allowance is, how it interacts with your savings, and the planning opportunities most people miss.
What the personal allowance is
Everyone resident in the UK gets a personal allowance: the first slice of annual income that’s free from Income Tax. For 2024/25 and 2025/26 it’s £12,570 — frozen at that level since 2021, a freeze that quietly drags more people into tax each year as wages rise (the infamous “fiscal drag”). Earn £12,570 or less and you pay no Income Tax at all. Earn more and you pay 20% on the slice from £12,571 to £50,270 (basic rate), 40% above that to £125,140 (higher rate), and 45% beyond. The allowance shrinks by £1 for every £2 earned over £100,000, disappearing entirely at £125,140 — creating a notorious 60% effective marginal rate in that band.
Crucially, the allowance applies to your total income — salary, self-employment profits, pension income, rental income and savings interest combined. It’s not per source. The full rate structure is on GOV.UK’s Income Tax rates pages.
How it affects your savings: the allowances stack
Here’s where it gets interesting — and where most people overpay tax through ignorance. Beyond the personal allowance, savers get additional tax-free slices specifically for savings income: the personal savings allowance (£1,000 of savings interest tax-free for basic-rate taxpayers, £500 for higher-rate, £0 for additional-rate) and the starting rate for savings (up to £5,000 of savings interest taxed at 0% for those whose non-savings income sits within the personal allowance).
Worked example: you’re retired with an £11,000 pension (within your personal allowance, so no tax) and £6,000 of savings interest. The starting-rate band covers £5,000 of that interest at 0%, and your £1,000 personal savings allowance covers the rest — total tax on £17,000 of income: £0. Thousands of low-income savers don’t realise this stack exists and either pay tax unnecessarily or avoid saving altogether. If your total income is modest, check whether you’re owed a rebate — HMRC won’t always find you.
What this means for ISAs (and when you don’t need one)
The ISA’s tax-free wrapper is valuable — but its value depends on whether you’d pay tax without it. A basic-rate taxpayer with £10,000 in a 4.5% savings account earns £450 interest — within the £1,000 personal savings allowance, so no tax due anyway. The ISA adds nothing today. But ISAs protect against the future: allowances can shrink, your income may rise into higher-rate territory (where the allowance halves), and interest compounds — today’s £450 could be tomorrow’s £2,000 as the pot grows. The ISA is insurance against your future tax position, and it costs nothing to use. See GOV.UK’s official ISA guidance for the full rules; the strategic point here is that the personal allowance stack determines how urgently you need the wrapper.
One more interaction: salary-sacrifice pension contributions reduce your taxable income, which can pull you back within allowances — a higher-rate taxpayer sacrificing down to £50,270 regains the full £1,000 savings allowance and avoids 40% tax simultaneously. The allowances don’t exist in isolation; they reward joined-up planning.
Personal allowance and part-time or low earners
If you earn under £12,570 — part-time workers, students, stay-at-home parents with small freelance income — the personal allowance means you pay zero Income Tax, full stop. But two things still deserve attention. First, National Insurance works differently: you start paying Class 1 NICs at a lower threshold (the primary threshold, around £12,570 too in recent years, but check current figures), and critically, earning too little can mean missing qualifying years toward your state pension — 35 are needed for the full amount. If you’re under the threshold, consider voluntary Class 3 contributions; they’re often outstanding value. Second, don’t waste the tax-free space: if your income is well below the allowance, you have unused tax-free capacity — pension contributions (which get tax relief even for non-taxpayers, up to £3,600 a year gross) or realising capital gains within allowances can use it productively. And if you’re married, the Marriage Allowance lets you transfer £1,260 of unused personal allowance to a basic-rate-taxpaying spouse — worth around £250 a year, claimed in minutes on GOV.UK, and still missed by hundreds of thousands of eligible couples.
Planning opportunities most people miss
Use it or lose it, annually: the allowance resets every 6 April and doesn’t carry over — if you can time income (bonuses, freelance invoices, pension withdrawals) across tax years, spreading it keeps more within allowances. Couples: allowances are individual — a couple has £25,140 of personal allowances plus two savings allowances; shifting savings into the lower-earning partner’s name (genuinely, not artificially) can save real tax. The £100k trap: earning £100,000–£125,140 faces that 60% effective rate as the allowance tapers — pension contributions pulling you below £100,000 are extraordinarily valuable here. Claim what’s yours: if you’ve overpaid because allowances weren’t applied (common with savings interest and new pensioners), you can reclaim from HMRC — and if the paperwork confuses you, our self-assessment guide walks through the system, while our explainer on getting a Unique Taxpayer Reference covers registration.
The bottom line
The £12,570 personal allowance is just the foundation — stacked with the savings allowances and the starting rate, it means many Britons with modest incomes can earn £18,000+ tax-free if their affairs are arranged well. The allowance rewards those who understand it: timing income across tax years, using both partners’ allowances, protecting the £100k boundary, and knowing when the ISA wrapper matters and when the allowances already cover you. Twelve thousand five hundred and seventy pounds of tax-free income, every year, use-it-or-lose-it. Make sure you’re using all of yours.
Review your allowances every spring when the new tax year begins — ten minutes with last year’s figures often reveals money left on the table.
Frequently Asked Questions
What is the UK personal allowance?
£12,570 for 2024/25 and 2025/26 — the amount of annual income free from Income Tax. Frozen since 2021, it pulls more people into tax each year as wages rise.
Does the personal allowance apply to savings interest?
It applies to total income including savings interest — plus savers get extra allowances: the personal savings allowance (£1,000/£500/£0 by tax band) and potentially the £5,000 starting rate at 0%.
What happens to the personal allowance over £100,000?
It tapers by £1 for every £2 earned above £100,000, vanishing at £125,140 — creating a 60% effective marginal rate in that band. Pension contributions can pull you back below it.
Can couples share personal allowances?
Allowances are individual and can’t be transferred (except the small Marriage Allowance) — but couples can arrange savings and income between them to use both sets fully.
Do I need an ISA if I’m within my allowances?
Not urgently today — but ISAs protect against future allowance cuts, rising income, and compounding growth pushing you over. Since they cost nothing, using one is cheap insurance.
