Outsourcing payroll in the UK: what it includes and how to switch

What a fully managed payroll service includes

A fully managed payroll service takes the entire payroll cycle off your desk, not just the calculations. That means every pay run is processed on schedule — weekly, fortnightly or monthly, covering salaried and hourly staff alike — with Real Time Information submissions, the Full Payment Submission and Employer Payment Summary, filed with HMRC on or before payday every single time, because HMRC treats late RTI filing as a compliance failure in its own right. It also covers the paperwork employees actually see: payslips, P60s at year end, and P45s when someone leaves. New starters are set up correctly from day one, leavers are processed cleanly, and statutory payments — sick pay, maternity and paternity pay, and similar — are calculated to the letter. Pension auto-enrolment is reassessed at every single pay run, not annually, with contributions uploaded directly to your pension provider. And crucially, there's a UK-based person you can actually call when something needs an answer, rather than a portal or an offshore queue.

• Every pay run processed — weekly or monthly, salaried and hourly staff.
• RTI submissions (FPS/EPS) filed with HMRC on time, every time.
• Payslips, P60s and P45s produced accurately and compliantly.
• New starters and leavers handled, statutory pay calculated.
• Pension auto-enrolment assessed each run, with uploads to your provider.
• A UK-based human to call when something needs answering.

The part most providers skip: paying less

Most payroll bureaus process what they're given: they take your employee data, run the numbers, file the RTI submissions, and stop there. That keeps you compliant, but it does nothing to reduce what you actually pay. The reason businesses switch to PayrollSmart is the optimisation layer we run on top of standard processing. We check whether the Employment Allowance is being claimed in full — and backdated if it's been missed in previous years, within HMRC's normal time limits for retrospective claims. We check that every employee is on the correct National Insurance category letter, because a wrong category — missing an under-21 or apprentice code, for example — means you're paying employer NI you don't legally owe. And we check that every other relief your business is entitled to is actually being applied, rather than assumed. Processing keeps you out of trouble with HMRC. Optimisation is what turns payroll from a cost centre into money you get back.

A worked example: what unclaimed reliefs really cost

Here's what the numbers look like for a typical small employer. Take a business with 8 employees, each earning £30,000 a year, paid monthly. Under the 2025/26 rates confirmed in HMRC's guidance on rates and thresholds for employers, the employer (secondary) Class 1 National Insurance threshold is £5,000 a year, and the secondary NI rate above that threshold is 15%. For each employee, that's £25,000 of earnings subject to employer NI — £30,000 minus the £5,000 threshold — which comes to £3,750 in employer NI per employee, or £30,000 across the whole team before any reliefs are applied. The Employment Allowance, confirmed on GOV.UK's claim-Employment-Allowance guidance, lets an eligible employer reduce that annual employer NI bill by up to £10,500 — and since April 2025 the eligibility cap tied to the previous year's NI bill has been removed, so any qualifying employer can claim the full amount regardless of how much NI they paid the year before. Claimed correctly, this business pays £19,500 in employer NI instead of £30,000. Left unclaimed — which happens more often than you'd expect, particularly after a change of accountant or payroll software — that's £10,500 a year, or roughly £875 a month, quietly overpaid to HMRC for no reason at all. That single figure is usually enough on its own to cover a managed payroll service several times over, which is exactly why checking it is the first thing we do on any free review.

How switching works

Switching payroll provider sounds like it should be disruptive — it isn't, when it's done properly. We migrate you free of charge, and the process is designed to be invisible to your staff. First, we collect your year-to-date figures, employee records, and current NI category letters and tax codes from your existing provider or software, whether that's another bureau, an in-house system, or spreadsheets. Second, we replicate your payroll in parallel before going live, checking the numbers reconcile against what you've been running so nothing shifts unexpectedly on the next payslip. Third, we take over from the next pay run — in as little as 24 hours from the point we have your data — so there's no gap in cover and no missed RTI submission during the handover. Your employees notice nothing except that payslips keep arriving on time, in the same format, for the same amount they expect. The only thing that changes on your end is who you call when you have a question.

And because there are no long-term contracts, you're never locked in — we keep your business by running payroll properly and saving you money, not with exit fees.

When outsourcing makes sense

There are a handful of clear signals that it's time to hand payroll to a specialist rather than keep running it in-house. If a director or office manager is spending several hours every month on payroll admin — chasing timesheets, working out statutory pay, double-checking NI codes — that's time being spent on a task that doesn't need business-owner attention and carries real downside if it's wrong. If you've already had a late-filing or late-payment penalty from HMRC, that's a signal the current process has a gap in it, because HMRC's penalty structure for PAYE and NI escalates the longer the problem goes unaddressed. If pension auto-enrolment assessments are being done by hand each run rather than automatically, that's a compliance risk waiting to surface at the next check. And if nobody has ever actually checked whether you're claiming the Employment Allowance in full, there's a strong chance you're one of the many UK employers quietly leaving money on the table. In most of these situations, the service pays for itself out of the savings it uncovers alone — which is exactly why the free payroll review exists: you see the real numbers for your business before you commit to anything.

Common mistakes businesses make running payroll in-house

Most of the payroll problems we see when we take over a new client aren't caused by carelessness — they're caused by payroll being treated as an administrative afterthought rather than a specialist function, done by someone whose real job is something else entirely. The same handful of mistakes turn up again and again, and each one carries either a financial cost, an HMRC penalty risk, or both. Some are one-off errors that compound every pay run until someone notices; others are simply reliefs and reviews nobody had time to get around to. None of them are unusual — they're the normal result of payroll being squeezed between other priorities in a growing business. Here's what we find most often when we review a new client's payroll for the first time, roughly in order of how frequently they show up and how expensive they turn out to be once totalled over a full tax year:

• Employment Allowance never claimed, or not backdated when it was missed in previous years.
• Employees left on the wrong NI category letter after a birthday, visa change, or apprenticeship ending.
• RTI submissions filed late or not reconciled against actual payment dates, triggering penalty risk under HMRC's escalating late-payment structure.
• Auto-enrolment reassessed only occasionally instead of every pay run, missing employees who cross the earnings threshold mid-year.
• P45s and P60s produced late or with errors, causing problems for employees at tax return time or when starting a new job.
• No single person owns payroll, so when the one person who understands it is on leave, deadlines get missed.

Edge cases to plan for

Two situations catch out businesses more often than the standard scenarios above, and it's worth knowing about both before they become a problem. The first is Employment Allowance eligibility for very small companies: a limited company where the director is the only employee paid above the secondary threshold does not qualify for the Employment Allowance under HMRC's rules, even though the business might otherwise look eligible on paper — so if you're a single-director company that's just taken on your first employee, don't assume the £10,500 allowance applies automatically until eligibility has actually been checked against your specific set-up. The second is mixed pay frequencies: many growing businesses end up running weekly payroll for hourly or temporary staff alongside monthly payroll for salaried employees, and each pay run needs its own RTI submission and its own auto-enrolment assessment on the correct cycle — treating them as one combined process, or only assessing pensions on the monthly run, is a common way mid-year joiners on the weekly payroll get missed entirely. Both are easy to handle correctly with the right process in place, but both are easy to get wrong if payroll is being run ad hoc.

How long does it take to switch payroll providers?

With PayrollSmart, migration is free and can be completed in as little as 24 hours once we have your payroll data — your year-to-date figures, employee records and current NI codes. We run your first payroll in parallel to check it reconciles before we go live, so there's no gap in RTI filing and nothing changes for your employees except who's running things behind the scenes.

Do I lose control if I outsource payroll?

No — you approve each run before it's finalised and you can see everything: payslips, RTI submissions, pension uploads, the lot. What you lose is the admin and the deadline risk, not the visibility or the final say.

What does outsourced payroll cost?

It depends on headcount and pay frequency, but for most businesses the reliefs and savings we find — starting with a properly claimed Employment Allowance, worth up to £10,500 a year under the 2025/26 rates — cover the fee many times over. The free payroll review shows you both sides of that maths, cost against savings, before you decide anything.

Does every business qualify for the Employment Allowance?

No. HMRC's eligibility rules exclude some employers, including limited companies where the director is the only employee paid above the secondary NI threshold. Most small and medium employers with genuine staff do qualify, and since April 2025 there's no cap based on your previous year's NI bill — but eligibility is worth checking properly rather than assuming, which is part of what the free review covers.

What happens if I've already missed a payroll deadline or filing?

HMRC's penalties for late PAYE and NI payment escalate with the number of defaults in a tax year — starting at 1% of what's late and rising to 4%, with additional 5% surcharges if tax is still unpaid after 6 and 12 months. If you've already had a penalty, it's usually a sign the current process has a structural gap rather than a one-off mistake, and switching providers stops it happening again rather than just fixing the immediate issue.