Manufacturing payroll is where simple mistakes get expensive fast. You're juggling shift differentials for second and third shift workers (typically $1-3/hour premiums), overtime calculations that stack on top of those differentials under FLSA rules, and piece-rate pay that has to be blended into overtime calculations correctly. Get any of that wrong and you're looking at Department of Labor audits that can reach back two years, or three if they find willful violations. Union shops add another layer with collective bargaining agreements that dictate pay scales, seniority bumps, grievance procedures, and reporting requirements that your payroll system needs to handle without manual workarounds.
Multi-plant operations create their own headaches. Each facility may fall under different state tax jurisdictions, different workers' comp classification codes (and rates that vary wildly by job function), and different local ordinances. A press operator in Ohio and a press operator in Texas might do the same job but carry completely different payroll configurations. If you're doing government contract work, prevailing wage requirements under the Davis-Bacon Act mean tracking certified payroll separately for those projects. Many manufacturers also employ a bilingual workforce, so self-service portals and training materials need to work in Spanish at minimum.
Time and attendance tracking is the backbone of everything else in manufacturing payroll. You need clock-in systems that handle shift swaps, break compliance, and automatic overtime flagging before it blows up your labor budget. Safety training records tie directly into OSHA compliance and workers' comp audits, so your HR system should track certifications and expiration dates without someone maintaining a spreadsheet on the side. The manufacturers that get payroll right tend to pick platforms built for hourly-heavy, multi-shift environments rather than trying to force-fit a system designed for salaried office workers.