Senior Human Resources Generalist - Manufacturing

About the job Senior Human Resources Generalist

Castelion is bringing a new approach to defense development and production: one that focuses on short, iterative design cycles, rapid testing in development, and modern commercial manufacturing strategies for production at scale. We're designing, building, and testing next generation long range strike weapons systems to give America and its Allies a definitive edge and deter future conflicts.
Senior Human Resources Generalist
Human Resources Generalist will lay a foundational role in building and optimizing the core people infrastructure that enables our teams to do their best work-on the ground and beyond.

You'll design, implement, and continuously improve critical HR systems and processes across onboarding, payroll, benefits administration, and people analytics. Partnering closely with leadership and cross-functional teams, you'll help create scalable, compliant, and employee-centric experiences that support rapid hiring and operational complexity.

Payroll Operations

Deliver 100% on-time payroll processing with little to no error rate.
Serve as first point of contact for payroll tax inquiries, notices, and agency communications.
Ensure timely and accurate payroll tax filings, reconciliations, and reporting across federal, state, and local jurisdictions, meeting all deadlines to avoid penalties.
Resolve payroll discrepancies and inquiries within 24-48 hours.
Ensure compliance with multi-state wage and hour laws, tax regulations, and reporting requirements.
Continuously improve payroll processes to support rapid scaling through automation and system optimization.
retirement, leave management, health insurance) to increase employee participation and satisfaction.
People Analytics & HR Systems
Maintain HRIS integrity and ensure accurate, real-time employee data.
Translate data into actionable insights for leadership and workforce planning.
Ensure Day 1 readiness for all new hires (e.g., new hire documentation, new hire checklist, compliance requirements).
Maintain 95% new hire satisfaction score on onboarding surveys.
General HR Operations
Support onboarding and offboarding with a seamless, high-quality experience.
Identify opportunities to automate, streamline, and strengthen HR processes.
Bachelor's degree in Human Resources, Business, or related field

• 3+ years of HR experience with strong ownership of payroll and benefits
• Proficiency with HRIS platforms (e.g., Rippling, ADP, Workday, or similar)
• Strong analytical skills (excel required; dashboards/BI tools a plus)
• Experience building or scaling HR processes from the ground up

HR certification (PHR, SHRM-CP, or equivalent)
Payroll certification (CPP or equivalent)
Leadership Qualities
Bias to Action and Creative Problem Solving . Successfully bring in applicable processes/concepts/materials from other industries to achieve efficiency gains. Trusted in previous roles to be voice of company with regulators, suppliers, gate keepers and customers. All employees are granted long-term stock incentives as part of their employment as Castelion. All employees receive access to comprehensive medical, vision, and dental insurance, and the company offers three weeks of paid time off per year.
Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.
S government-issued security clearance, it may in the near future. S. government-issued security clearance is required. S. citizens are eligible for a security clearance.