How is the FLSA regular rate of pay calculated for overtime?

When an employee earns multiple rates or non-discretionary pay in a workweek, FLSA requires a weighted average: Regular Rate = Total Straight-Time Earnings ÷ Total Hours Worked. Straight-time earnings include base wages, shift differentials, certification pay, longevity stipends, and non-discretionary bonuses, not just the primary hourly rate.

What is the formula for qualified overtime premium under Code TT?

Qualified overtime premium = (Regular Rate × 0.5) × FLSA Overtime Hours. Only the 0.5x premium above the regular rate is reportable in W-2 Box 12, Code TT, not total overtime dollars or contractual double-time above FLSA thresholds.

Why do legacy ERP systems fail FLSA overtime premium calculations?

Most public sector ERP platforms were configured to calculate overtime against a fixed base or primary hourly rate. When employees receive certification pay or shift differentials, the system calculates the 0.5x premium against base rate only, understating Code TT and producing inaccurate W-2s.

What is the FLSA Section 207(k) overtime threshold for fire and police?

Under Section 207(k), public safety employers may use work periods up to 28 days. Firefighters trigger FLSA overtime at 212 hours per 28-day period; law enforcement at 171 hours. Most weekly/bi-weekly payroll systems do not natively track cumulative hours across these extended periods.

Does Code TT include double-time or holiday premium pay?

Only the FLSA-required portion counts. Contractual overtime above the FLSA minimum (such as double time) and holiday premiums when no FLSA overtime is triggered are excluded. Comp time is different: for public employees under FLSA §207(o), qualified overtime counts when comp time is used or cashed out (IRS Fact Sheet FS-2026-13, Question 18).

Why Your ERP Is Probably Miscalculating the Overtime Premium (And What the IRS Will Do About It in 2026)

Legacy ERP systems calculate overtime against base rates, not the FLSA regular rate. That understates the qualified premium for W-2 Box 12, Code TT, and the employee loses part of the deduction.

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