Senior Payroll Specialist (UK Payroll)

About the role

Amentum is looking for an experienced, independent Senior Payroll Specialist with strong UK payroll expertise. The selected candidate will be employed by Critical Mission Services Sp. z o.o., part of Amentum. The role suits someone with a proactive, hands-on approach, a focus on continuous improvement and a collaborative mindset.

Key responsibilities

• Process end-to-end payroll for assigned countries/entities, including new hires, changes, terminations, variable pay and adjustments, and validate inputs against policy and statutory requirements
• Review and approve outputs from external payroll vendors, identify discrepancies and run root cause analysis
• Run payroll validations, gross-to-net analysis, payment reviews, variance analysis and balancing, and prepare management, statutory and ad hoc reports
• Act as a key contact for employees, HR, Finance, Benefits, Tax and vendors, and handle escalated inquiries
• Support month-end, quarter-end and year-end activities, including wage and tax adjustments and statutory reporting
• Maintain and improve payroll documentation, SOPs and process flows, and monitor legislative changes
• Train and mentor team members, support the Payroll Supervisor/Manager and act as deputy during their absence
• Take part in payroll transformation projects, UAT and vendor coordination

Required profile

• Bachelor's degree in Finance, Accounting, Business Administration or a related field
• Fluency in written and spoken English
• Minimum 4 years of payroll experience, preferably on complex or global payroll for organisations with 1,000+ employees
• Experience with outsourced payroll providers and payroll systems in a multinational environment

Required skills

• Strong understanding of payroll legislation, controls and reconciliation
• Advanced Excel (Pivot Tables, XLOOKUP/VLOOKUP, formulas, filtering, data analysis)
• Proficiency in Word and PowerPoint

What we offer

• Full-time employment with a competitive salary, benefits package and flexible working hours (7:30-10:00 start)
• Short Fridays (8.5 hours Mon-Thu, 6 hours on Friday) and hybrid or stationary work
• Medical, dental and vision insurance, paid time off, retirement benefits, parental leave and employee wellbeing support
• Training in industry-leading tools and participation in global projects