HR Administrator in London

The HR Administrator is the operational backbone of the Flatpay UK People team. This is a high-volume, detail-critical role with onboarding at its core — coordinating up to 100 new starters each month, from logistics and accommodation through to HRIS setup and contract administration. You will work closely with the Head of HR and HR Advisor, executing the day-to-day administration that keeps the People function accurate and running at pace. The role suits someone who takes genuine pride in getting the detail right, manages competing priorities without dropping the ball, and understands that in a scaling business, clean HR admin is the foundation everything else is built on.

What you'll do

• Onboarding Coordination
  • Coordinate end-to-end onboarding logistics for up to 100 new starters per month, including accommodation booking, catering, and travel arrangements for multi-day cohort programmes.
  • Create and configure new starter profiles on Personio ahead of day one, ensuring all data is accurate, complete, and compliant before the employee arrives.
  • Collect and verify pre-employment documentation — right to work, signed contracts, and new hire information.
  • Act as the day-of point of contact for new cohorts, ensuring a smooth, well-organised, and welcoming first-day experience.
• HR Administration & Records
  • Maintain accurate, up-to-date employee records in Personio across the full employee lifecycle, from contract issue through to offboarding.
  • Draft and issue contract variation letters for role changes, promotions, salary adjustments, and department transfers, ensuring all changes are reflected in the HRIS on the same day they are confirmed.
  • Process leavers in Personio, coordinating with payroll to ensure accurate final pay and completing all associated administrative steps on time.
• First-Line Employee Queries
  • Serve as the first point of contact for standard employee queries, providing clear, accurate answers grounded in the Employee Handbook — covering areas such as annual leave, sickness reporting, expenses, and working hours.
  • Direct any complex, sensitive, or ER-related queries to the HR Advisor or Head of HR promptly, without attempting to resolve matters outside this scope.
  • Maintain a consistent, professional, and helpful tone in all employee communications, reflecting the standards of the People team.
• General HR Operations
  • Support the HR team with administrative tasks across the employee lifecycle as required, including filing, correspondence, and system updates.
  • Keep onboarding trackers, administrative documentation, and people data accurate and current at all times.
  • Contribute to a People function that runs efficiently, accurately, and at pace with business growth.

Who you are

• Exceptionally organised with strong attention to detail — able to manage a high volume of tasks simultaneously.
• Clear, professional communicator — written and verbal, with the confidence to give employees straightforward, accurate answers on policy and process.
• Comfortable working to tight deadlines in a fast-moving, high-growth environment.

Background & Requirements

• 1–2 years of administrative experience in a fast-paced environment; experience in HR is an advantage but not required.
• Demonstrably organised and detail-focused — able to give examples of managing high-volume, time-sensitive tasks accurately.
• Confident using systems and technology; prior experience with an HRIS (e.g. Personio, HiBob, or similar) is a plus but not essential.
• Right to work in the UK (visa sponsorship is not available for this role).

Why Flatpay?

• At Flatpay, how we work matters as much as what we achieve. Happy Humans — We bring energy to our work and create teams people enjoy being part of.
• No Assholes — We perform at a high level while treating colleagues and customers with respect.
• It’s Our Business, Own It — Everyone takes responsibility and manages their work like it’s their own business.
• Start With No — We challenge ideas, think commercially and focus on what truly creates value.
• Sky-High Ambitions — We set bold goals and expect people to keep raising the bar.
• The Best Argument Wins — Titles don’t decide outcomes. We debate openly to reach the best decisions.

About us

Welcome to Flatpay! Flatpay is not just another payment solution; we are dedicated to innovating the market for payment solutions and financial services in the SME segment with our customer-centric and transparent services. Today, we are one of the fastest-growing fintech companies out of the Nordics - and Denmark's fastest unicorn! Flatpay is more than just work. We believe in fostering a vibrant and fun work culture where our ambitious colleagues can thrive. As part of our team, you will be one of +2.000 passionate colleagues dedicated to making a difference in the world of payments. What sets Flatpay apart is our dedication. We continuously strive to stay ahead of the curve, adapting our solutions to meet our client's evolving needs. Let's shape the future of merchants together!