One step that reliably prevents underpayments on the first January payroll run is locking a "rate effective date audit" before year end, not after the new rates go live. In practice, this means running a pre January 1 payroll simulation by state and role using effective dates, not just updated rate tables. We verify that every employee record reflects the correct state, locality, exemption status, and pay type with the new minimum wage tied to a January 1 effective date. This catches cases where systems technically hold the new rate but don't apply it to specific worker profiles. A real edge case we caught using this step involved a remote employee who moved mid-year from one state to another with a higher January minimum wage. Their profile had been updated for tax withholding, but the work location field driving wage rules was still mapped to the original state. On paper, the new state rate existed in the system, but it wasn't being applied to that employee on the first run. Because we ran the effective date audit in December, the mismatch surfaced immediately in the simulated payroll output. We corrected the work location mapping before January 1, reran the simulation, and avoided a first paycheck underpayment that would have triggered a retro adjustment and compliance exposure. The key lesson is to test payroll the way the system actually executes it. Minimum wage failures rarely come from missing rates. They come from mismatched effective dates, locations, or employee classifications. Catching those in December removes the risk entirely.