Working graveyard hours or weekend shifts usually comes with a financial bonus: night shift differentials or premium shift pay. But how does the IRS treat these differential payments come tax season?
IRS Treatment: Gross Earnings vs. Supplemental Tax
A common myth among shift workers is that differential pay is taxed at a separate, higher rate. In reality, the IRS considers shift differentials, night premiums, and weekend extra pay as standard gross earned income.
They are subject to ordinary federal income tax rates, state income taxes, and FICA (7.65% for Social Security & Medicare).
The FLSA Regular Rate Calculation Trap
Under federal law, shift differentials must be included in your regular rate of pay before calculating overtime multiplier rates.
Example: If your base pay is $30/hr and you earn a $4/hr night shift differential, your base regular rate for night overtime is $34/hr. Your overtime rate must be calculated as $34 × 1.5 = $51/hr (not $45/hr + $4).
Why Your Paycheck Withholding Might Seem Higher
If your payroll software processes differential pay as a lump-sum adjustment or separate line item, employer payroll systems may apply standard supplemental tax withholding rates (22% federal flat rate). However, at year-end on your W-2, all earned wages are aggregated into Box 1.