Mellow vs Personio
The UK HR platform that Personio should have been
Built for UK. Not adapted for it.
Assistants that take action
Mellow’s agents generate contracts, run payroll estimates, start compliance workflows, and produce audit-ready documents — not just answer questions.
Personio
German-first, UK-adapted
50–2,000 employees
From ~£5+ PEPM (estimated)
Mellow
UK-built, UK-first
10–500+ employees
From £4/employee/month
Things to consider
- ✗No native UK payroll — exports to Xero/Sage, no HMRC RTI of its own
- ✗AI is a general assistant — no domain HR agents, no manager coaching
- ✗No IR35 determination engine
Feature comparison
| Feature | Mellow | Personio |
|---|---|---|
| Core HR | ||
| Employee records & documents | ||
| Onboarding workflows | ||
| Absence & holiday management | ||
| Payroll | ||
| Native UK payroll engine Full PAYE/NI calculation to the penny | Requires third-party payroll integration | |
| Native UK payroll + ready-to-file output PAYE, NI & statutory to the penny + BACS; produces a ready-to-file output (filing pack) | No native payroll | |
| P60 / P45 / P11D generation | ||
| Compliance | ||
| ERA 2025 compliance built in ERA 2025 changes mapped | Not UK-specific | |
| IR35 determination engine CEST-parity accuracy | ||
| Tribunal risk scoring | ||
| AI | ||
| Domain AI agents AI assistants included per tier — Employee, Payroll, Law, Pensions, IR35, Right-to-Work, up to the People Coach | General AI assistant + a recruiting agent (aurio, rolling out) — not a suite of domain assistants | |
| Employment Law Agent | ||
| Payroll Intelligence Agent | ||
| AI manager coaching (People Coach) Coaches managers through conflict & team dynamics, grounded in your own data | No manager-coaching agent | |
| People | ||
| Adjustments Passport Living per-employee record of agreed workplace adjustments — per-country legislation, AI-drafted wording | No equivalent — adjustments tracked ad hoc | |
| Team-health index from operational signals Live index fused from workload, ER cases, absence & recognition — no survey required | Engagement surveys (eNPS/pulse) — not a fused operational-signal index | |
| Performance | ||
| Performance reviews & PIPs | ||
| Recruitment | ||
| Applicant tracking (ATS) | ||
| Workforce | ||
| Workforce planning | ||
Our take
Personio is a well-regarded European HR platform trusted by thousands of businesses. For UK companies specifically, the question is whether you need a platform adapted for the UK or one built for it. Native UK payroll, IR35 determination, and ERA 2025 compliance aren't add-ons in Mellow — they're the foundation. If those are your priorities, that distinction matters.
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