Business payroll looks like a solved problem — software calculates, HMRC receives, staff get paid — right up until it isn't: a missed pension re-enrolment, an FPS filed late for the third month running, a minimum-wage breach built into a salary-sacrifice scheme nobody re-checked in April. Payroll is where more compliance regimes intersect than anywhere else in a small business — PAYE, NIC, pensions, statutory pay, minimum wage, holiday law — and each moves on its own calendar. Here is the 2026/27 map, and the honest in-house-versus-outsourced question at the end.
The core cycle: RTI and the money
Every pay run files a Full Payment Submission on or before payday — the real-time information rule that turned payroll from a year-end exercise into a per-run deadline. Late filings attract monthly penalties scaled by headcount (£100 for the smallest employers up to £400 for 250+, with one free default a year), and persistent lateness is a visibility problem beyond the fines: RTI data now feeds everything from universal credit to HMRC risk profiling. The remittance side runs to the 22nd of the following tax month (electronic; smaller employers can pay quarterly), with the employer cost stack for 2026/27 standing at 15% NIC above £5,000 per head — softened by the £10,500 Employment Allowance for those who claim it — and the 0.5% apprenticeship levy above a £3 million pay bill.
Pensions: the duties that never finish
Auto-enrolment is a permanent state, not a setup task: eligible staff (earning over £10,000, aged 22 to state pension age) enrolled into a scheme with minimum contributions of 8% of qualifying earnings (£6,240–£50,270), at least 3% from the employer; new joiners assessed every run; opt-outs processed and refunded correctly; and — the one that catches everyone — re-enrolment every three years with a re-declaration to the Pensions Regulator, a duty that arrives silently and carries penalties for the forgetful. Two live wrinkles for 2026: pension schemes complete their connection to the pensions dashboards by the end of October, which will surface employees' questions about old pots to whoever runs payroll; and the 2029 cap on salary-sacrifice NIC relief means sacrifice schemes deserve a strategic look while the current treatment lasts.
Statutory payments and the floor rules
The statutory rates move every April and payroll must move with them: SSP at £123.25 a week or 80% of average weekly earnings, whichever is lower — the "or 80%" limb is new with the 2026 sick-pay reforms and matters for low-paid and part-time staff; SMP at 90% of average weekly earnings for six weeks, then £194.32 or 90% of earnings, whichever is lower; and the minimum wage floor — £12.71 for workers aged 21 and over, with lower rates for younger workers and apprentices — policed against deductions, uniforms and unpaid time, not just headline rates. Around them sit the quieter obligations: itemised payslips showing hours where pay varies, holiday pay for variable-hours staff usually computed on the 52-paid-week average (with rolled-up holiday pay available for qualifying irregular-hours and part-year workers), and — since April 2026 — six-year retention of leave and holiday-pay records under the Employment Rights Act. Payroll is where employment law becomes arithmetic, and tribunals read the arithmetic.
The failure patterns, and the annual review that prevents them
Across the payrolls we take over, the same faults recur: the Employment Allowance never claimed (or claimed in the wrong group company); April rate changes applied to new starters but not legacy salary-sacrifice arrangements; re-enrolment missed because the three-year date lived in a departed manager's calendar; benefits handled inconsistently between payroll and P11D, about to matter more as payrolling becomes mandatory from 2027; and director-only payrolls running settings copied from a five-employee template. None of these is sophisticated; all of them cost real money or real penalties. The fix is a standing April review — rates, thresholds, allowances, sacrifice schemes against the new NMW, pension settings, benefits strategy — treated as part of the year-end cycle rather than an optional extra.
In-house or outsourced: the actual trade-off
In-house payroll buys control and immediacy at the price of key-person risk and the burden of staying current across every regime above; outsourced payroll buys a team that processes hundreds of runs a month — for whom April changes, re-enrolment dates and SSP reforms are routine — at the price of needing a clean data flow for starters, leavers and variations. The honest heuristic: below a few hundred employees, outsourcing usually wins on cost and risk unless payroll is genuinely strategic to the business; above that, hybrid models dominate. Either way, the accountability stays with the employer — which is why the choice of provider matters as much as the choice to outsource.
Acumon runs payroll for businesses from two employees to group scale — managed and fully outsourced, with auto-enrolment, PAYE and the April review built in, and a payroll audit for anyone who suspects their current setup contains one of the faults above. It usually does; the audit is how you find out which one.