Building an onboarding plan in the United Kingdom
Reviewed by Mellow Editorial Team, HR & payroll content team
A well-structured onboarding plan ensures new hires are legally compliant, properly set up on payroll, and productive from day one — it is not simply a welcome lunch and a laptop.
Confirm the right to work before anything else
Before a new employee sets foot in the office or starts remotely, you must carry out a right-to-work check. This is a legal requirement. You check original documents (passport, share code, biometric residence permit) and keep a copy on file. Failure to do this correctly exposes you to a civil penalty of up to £60,000 per illegal worker.
For British and Irish citizens, a passport or birth certificate plus National Insurance number is sufficient. For nationals who require permission to work in the UK, use the Home Office online checking service and record the outcome. Do this before day one, not after.
Set up payroll and notify HMRC
Once you have a start date confirmed, you need to register the employee on your payroll software and gather their details: full name, date of birth, address, National Insurance number, and their starter declaration (P46 equivalent, now collected via your payroll software).
The starter declaration tells you which tax code to apply from the outset. Getting this wrong means the employee pays the wrong amount of income tax from the first pay run.
On each payday, you are required to submit a Full Payment Submission (FPS) to HMRC under Real Time Information (RTI) — on or before the date the employee is paid, not after. Employer National Insurance contributions sit at 13.8% on earnings above the secondary threshold, and employees pay 8% up to the upper earnings limit, then 2% above it. The personal allowance remains £12,570 for 2026/27, meaning earnings below this are not subject to income tax.
If you offer a workplace pension — which you must for eligible workers — auto-enrolment requires a minimum employer contribution of 3% and a total minimum contribution of 8% of qualifying earnings (meaning the employee contributes at least 5%). Enrol eligible employees by the end of the assessment period, which is typically the first pay run. Missing the enrolment window triggers re-enrolment obligations and potential fines from The Pensions Regulator.
Prepare the employment contract and statutory documents
Under current UK law, employees must receive a written statement of particulars on or before day one. The Employment Rights Act 2025 has reinforced and extended day-one rights, so this is not an area to delay or treat as administrative housekeeping.
The written statement must cover: job title and description, start date, pay and pay frequency, working hours, holiday entitlement, notice periods, and sick pay arrangements. Statutory annual leave stands at 5.6 weeks — that is 28 days including bank holidays for a standard five-day week. Statutory Sick Pay and statutory family-leave pay (maternity, paternity, shared parental) all apply from day one regardless of length of service, under the updated framework.
If your employee is part-time, calculate their leave entitlement on a pro-rata basis. Make sure your contract reflects actual working patterns, not a default full-time template.
Structure the first week deliberately
Compliance handled, the practical side of onboarding matters just as much for retention. A new hire who cannot log in to systems, does not know who to ask for help, or sits idle for two days forms a lasting negative impression.
A practical first-week structure:
- Day one: IT access, building or remote access, introductions to the immediate team, and a walkthrough of essential tools.
- Days two and three: Role-specific orientation — key processes, ongoing projects, reporting lines, and where to find internal documentation.
- Days four and five: First meaningful work tasks, an introductory meeting with a manager to set 30-day objectives, and a check-in on how the week has gone.
Assign a buddy or point of contact for non-managerial questions. This reduces the cognitive load on a new starter and means they are not interrupting the same person repeatedly.
Create a 30-60-90 day framework
Onboarding does not end on Friday of the first week. A 30-60-90 day plan gives both the manager and the employee clear milestones and prevents the common situation where someone has been in post for three months but neither side is sure whether they are performing well.
- 30 days: Understand the role, the team, and core processes. Identify gaps in knowledge or access.
- 60 days: Operating independently on defined tasks. Feedback given and received. Probation review scheduled if applicable.
- 90 days: Demonstrating full competence in the role. Probation decision made and confirmed in writing.
Document these reviews. If performance issues arise later, written records of what was agreed during probation will matter. Under the Employment Rights Act 2025, unfair dismissal protections apply earlier than under the previous framework, which makes structured, evidenced onboarding even more important than it was before.
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