UK Workplace Pensions and Payroll Compliance

If your payroll platform serves UK employers, you know workplace pension compliance is not optional infrastructure. It's a legal obligation your customers carry, and if your platform gets it wrong, that obligation lands on them and leads to unhappy customers. In the first half of 2024 alone, The Pensions Regulator (TPR) exercised its auto-enrolment enforcement powers over 75,000 times and issued more than 20,000 fixed penalty notices. The employers receiving those notices weren't all negligent. Rather, many were running payroll software that handled the common cases correctly but quietly failed on the ones that weren't.

The mechanics your customers need you to get right

Auto-enrolment gets complicated quickly:

Eligibility is a per-period classification, not a one-time flag. Every pay period, every worker needs to be assessed against three categories: eligible jobholder, non-eligible jobholder, and entitled worker, based on their age and earnings in that specific period. A part-time employee whose hours increase, a variable-pay worker with a strong commission month, someone who turns 22: all of these can change a worker's category, and the change needs to be caught and acted on in the same payroll cycle it occurs in. A platform that only checks eligibility at onboarding and flags new starters will miss these mid-employment changes entirely.

Contribution calculations have a precision requirement that’s easy to underestimate. The 8% minimum contribution doesn't apply to gross salary — it applies to qualifying earnings, the slice of the employee's pay that falls within a legislated band (£6,240 to £50,270 annually for 2025/26 and 2026/27, prorated to match pay frequency). An employer configured for Qualifying Earnings who mistakenly applies 8% to full gross pay is overpaying relative to statutory thresholds, whereas an employer certifying under Set 3 (Tier 3) pays a lower rate (7%) on full gross pay from the first pound. Applying the wrong band calculation can also cause underpayments, which lead to compliance failures. Either way, the discrepancy compounds silently across every pay run until someone notices, causing a huge headache to fix after the fact.

Employers can also choose to base contributions on a pensionable pay definition rather than qualifying earnings — basic salary only, total earnings from the first pound, or a custom set of pay elements — as long as the result meets the statutory minimum. Your payroll platform needs to support all of these and apply them consistently per scheme configuration.

The three pension tax treatments affect different parts of the payroll calculation and sequencing matters. Under Net Pay Arrangement, the employee contribution reduces taxable pay before income tax is calculated, but doesn't affect National Insurance. Under Salary Sacrifice, both income tax and NI are calculated on a reduced salary, generating NI savings for both employee and employer that the other methods don't. Under Relief at Source, the payroll engine deducts the net employee contribution (80%) post-tax and post-NI, leaving taxable pay unchanged while the pension provider claims tax relief from HMRC. Because of this, calculation sequencing depends on the scheme: Salary Sacrifice reduces gross pay pre-tax and pre-NI, Net Pay Arrangement reduces taxable pay pre-tax but post-NI, and Relief at Source runs entirely post-tax and post-NI.

In practice, this means the pension flow has to run at the right point in the calculation pipeline: after gross earnings and benefits are resolved, but before PAYE and NI are calculated.

The obligations your customers don't know they have until they miss them

The parts of pension compliance that generate the most enforcement action are the ones that don't come up in the initial setup but surface months or years later:

Cyclical re-enrolment happens every three years. Employers must reassess workers who previously opted out and re-enrol those who qualify. A re-declaration of compliance must be submitted to TPR within five months of the third-anniversary date, not five months from your chosen re-enrolment date. Missing this cycle or miscalculating the deadline is a common source of enforcement action against otherwise compliant employers.

Postponement, which can delay initial enrolment by up to three months, cannot be applied at re-enrolment. Some workers are not assessed for re-enrolment: those already active members of a qualifying scheme and those who don't currently meet the eligible jobholder criteria. Others may be excluded by employer policy: workers who opted out within the previous 12 months, directors, and workers under notice of termination. These two layers of exclusions need to be handled separately, with the policy-driven exclusions configurable per employer rather than applied universally.

Opt-out refund processing carries the most downstream complexity of anything in the pension cycle. Because the law treats an opt-out as if the worker was never enrolled, all contributions must be reversed. Crucially, never reopen closed pay runs, simply process the reversal in your current payroll run to maintain consistency with past filings. Depending on whether your scheme uses Net Pay or Relief at Source, the payroll engine should automatically apply the correct tax and NI adjustments.

The window itself has a subtlety worth flagging: it starts from the later of 1) the membership creation date or 2) the date the employee received their enrolment communication. Both dates need to be in the data model. If the communication date lives in an HCM or comms system rather than the payroll engine, validating the window boundary requires a defined data contract between those systems. An opt-out processed outside the valid window is a compliance failure.

Provider integration is a maintenance commitment, not a 1-time build. NEST, Smart Pension, People's Pension, Aviva, Legal & General, Scottish Widows, Standard Life, and Royal London all have different integration methods, file formats, authentication requirements, and submission schedules. Rejection reports and acknowledgements must feed back into the system. Provider APIs change, new providers emerge, and keeping integrations current is an ongoing cost as your customer base grows.

What it means to power pensions through Intermezzo

Intermezzo's pension module is built into the core payroll calculation engine. For payroll software companies, that means the compliance depth described above is available through the same API calls that calculate PAYE and National Insurance rather than a separate integration or an added service tier.

Your customers get compliance coverage they can rely on. Eligibility assessment runs every pay period for every worker, with the correct three-category logic, prorated thresholds, and audit records regardless of outcome. Contribution calculations support qualifying earnings, pensionable pay, and custom definitions per scheme. All three tax treatment methods are handled correctly, with the pension flow sequenced at the right point in the calculation pipeline so that income tax and NI figures are always calculated on the right basis. The current thresholds are configurable with effective dating, so annual TPR (The Pensions Regulator) updates apply without a deployment from your team or ours.

Re-enrolment and opt-out processing are fully handled. Cyclical and immediate re-enrolment are treated as distinct pathways with the correct exclusion logic at both layers. Opt-out processing validates the window against both relevant dates, reverses all affected calculations across pay periods, and generates the provider correction record in the same run. Re-declaration of compliance reporting is included.

Provider integration is maintained by us, not you. Our architecture means contribution logic is provider-agnostic — adding or updating a provider doesn't touch the calculation engine. Current coverage includes NEST, Smart Pension, People's Pension, Aviva, Legal & General, Scottish Widows, Standard Life, and Royal London.

When regulations change, we carry the update cost. TPR reviews thresholds annually. The government has given itself the power to remove the lower qualifying earnings limit, with implementation subject to future regulations (Pensions (Extension of Automatic Enrolment) Act 2023), which would change contribution calculations for every employer. Minimum contribution rates could change. Each of these is a configuration update or a calculation logic change that sits on our roadmap, not yours.

Intermezzo is an AI-powered global payroll API used by payroll software providers such as UKG to power calculation, compliance, and filing across multiple countries. To discuss UK pension coverage or explore the API, book a demo with us below.