How does UK pension auto-enrolment work?

In plain English

Eligible workers are enrolled automatically; you do not need to opt in. The contribution structure is built around 'qualifying earnings' - the slice of pay between £6,240 and £50,270. The minimum total contribution is 8% of that slice, with 5% from the employee (which includes basic-rate tax relief) and 3% from the employer. Some employers contribute more or use total earnings instead of the qualifying band, which may indicate a more generous scheme than the statutory minimum.

Tax relief is delivered through one of two mechanisms. Relief at source deducts contributions from your net (after-tax) pay; the pension provider then claims back 20% tax relief from HMRC and adds it to your pot. If you pay higher- or additional-rate tax, you typically claim the extra relief through Self Assessment or your PAYE coding notice.

Net pay arrangements deduct contributions from gross pay before income tax is calculated, so relief at your full marginal rate is applied immediately. There is no need to claim higher-rate relief separately. Salary sacrifice is different again: you reduce gross salary in exchange for an equivalent employer pension contribution, which appears consistent with NI savings on the sacrificed amount for both employee and employer.

You can opt out within one month of enrolment to receive a refund of contributions. After that window, you can stop contributing but past contributions stay invested. Employers must re-enrol eligible workers every three years, which means a previously opted-out worker may notice deductions reappear without an obvious trigger. This does not prove an error and is consistent with the cyclical re-enrolment duty on employers.

Eligibility itself is worth understanding. To be auto-enrolled, you typically need to be aged between 22 and State Pension age, earn above £10,000 a year (the trigger for auto-enrolment), and ordinarily work in the UK. Workers aged 16-21 or State Pension age to 74 who earn above the lower earnings limit can opt in and still receive employer contributions, while those earning between the lower threshold (£6,240) and the trigger (£10,000) form a separate 'non-eligible jobholder' category with rights to opt in. Reviewing the assessment letter from the employer is usually the clearest source for confirming which category applies in any given pay reference period.

The choice of relief mechanism is set by the employer, not the worker. This matters because lower earners under net pay arrangements historically missed out on relief that relief-at-source members received automatically. From 2024/25 onwards, HMRC introduced a top-up for affected low-earners under net pay; payments may indicate as a separate credit and are not always visible on the payslip itself. If you earn between the personal allowance and the lower earnings limit and your scheme uses net pay, it is worth reviewing the annual statement to see whether the top-up has been applied.

Worked example (2026/27 figures)

Maya earns £30,000 on category A. Qualifying earnings are £30,000 − £6,240 = £23,760. Total minimum contribution: 8% = £1,900.80 a year. Of that, employer pays 3% (£712.80); employee gross contribution is 5% (£1,188).

Under relief at source, Maya's payslip deduction is 4% of qualifying earnings (£950.40), with HMRC adding the remaining £237.60 directly into the pension. Under a net pay arrangement, the full £1,188 is deducted before tax - saving 20% income tax (£237.60) immediately. The end pension contribution is the same; the timing and route differ.

Under salary sacrifice for the same £1,188, Maya's gross pay drops to £28,812. NI savings of approximately 8% × £1,188 = £95 may also accrue to Maya, plus 13.8% × £1,188 = £164 to the employer (which some employers share).

Multi-scenario worked example

Consider three colleagues earning different salaries on the statutory minimum scheme using qualifying earnings. Sam earns £18,000. Qualifying earnings = £11,760. Total contribution at 8% = £940.80; employee 5% = £588; employer 3% = £352.80. Under relief at source, the payslip deduction is £470.40 net and HMRC adds £117.60. Sam is a basic-rate taxpayer, so no further claim is required.

Priya earns £55,000. Qualifying earnings cap at the upper limit, so the band is £50,270 − £6,240 = £44,030. Total contribution at 8% = £3,522.40; employee 5% = £2,201.50; employer 3% = £1,320.90. Under net pay, the £2,201.50 comes off gross pay, giving 40% relief on the slice above £50,270 worth of taxable income - appearing consistent with full marginal-rate relief without a separate claim.

Tom earns £130,000 in a salary sacrifice arrangement contributing 5% of total pay (£6,500). Gross taxable pay drops to £123,500. The sacrifice may indicate income tax savings at the additional rate plus NI savings of 2% on the slice above the upper earnings limit, plus employer NI savings of 13.8% which the employer may pass through. Based on the figures provided, Tom's effective relief on the £6,500 contribution can exceed 60% once tapered personal allowance interactions near £100,000 are considered. This does not prove a saving in every case - high earners should review with a regulated adviser.

Common mistakes people make

• Forgetting to claim higher-rate relief under relief-at-source schemes.
• Opting out without realising the long-term cost in lost employer contributions.
• Confusing qualifying earnings with total earnings - they often differ.
• Assuming all schemes are salary sacrifice - many are not.
• Missing the one-month opt-out refund window.
• Believing the 8% minimum is the optimal contribution - many advisers suggest higher percentages for adequate retirement income.
• Assuming the personal allowance applies to qualifying earnings - it does not; the £6,240 lower limit is separate from the £12,570 PA.
• Thinking the employer must use the statutory minimum - many enhanced schemes contribute on total earnings or at higher percentages.
• Overlooking the cyclical re-enrolment notice and being surprised by reinstated deductions every three years.
• Treating salary sacrifice as risk-free - it can reduce statutory benefits like maternity pay, mortgage affordability assessments, and life cover that are based on gross salary.

When this might apply to you

1. You started a new job and notice a pension deduction on your first payslip.
2. You are a higher-rate taxpayer and want to check whether you need to claim extra relief.
3. Your employer offers salary sacrifice and you want to compare options.
4. You are approaching State Pension age and are reassessing contributions.
5. You stopped contributing and have just received a re-enrolment notice.
6. You receive a large bonus and the pension deduction in that month appears unusually high - qualifying-earnings schemes typically include bonuses.
7. You have moved to a part-time role and your annual earnings have dropped close to the £10,000 trigger, which may indicate a change in eligibility.
8. You earn below the personal allowance under a net pay scheme and want to check whether the HMRC top-up for low earners has been applied.

What to do step by step

1. Find your scheme name and provider on your payslip or pension portal.
2. Confirm whether it is relief at source, net pay, or salary sacrifice.
3. Check the contribution percentages and the basis (qualifying earnings vs total earnings).
4. Verify the employee deduction shown matches the agreed percentage on the most recent payslip.
5. If higher-rate, ensure additional relief is being claimed via Self Assessment or your PAYE coding notice.
6. Review your annual benefit statement for contributions paid in and projected retirement income.
7. Use our payslip check to verify deductions appear consistent.

When to contact HMRC, payroll, or a professional

Speak to payroll for scheme details and contribution levels. Contact HMRC to claim higher-rate relief outside Self Assessment. A regulated financial adviser can help if you are weighing opt-out, salary sacrifice, or consolidation decisions. The Pensions Regulator publishes guidance for workers and employers, and MoneyHelper offers free, impartial pension guidance for workers who are unsure where to start.

Frequently asked questions

Related guides and tools

• Payslip line by line
• NI categories
• Tax codes explained
• PAYE: cumulative vs non-cumulative
• Pension contribution calculator
• Take-home pay calculator
• Run a free payslip check

Educational content only; not regulated financial advice.