Regular Rate Audit

W-2 Box 12 Code TT: The Employer's Guide to Calculating Qualified Overtime Compensation (2026)

By Nick Peterson — software engineer; I build payroll-audit computation. Educational information, not legal or tax advice. Every claim links a primary source. Updated July 20, 2026.

Starting with tax year 2026, every employer that pays overtime to non-exempt employees must report a number on the W-2 that most payroll systems have never computed as a stored, separable field: qualified overtime compensation, in Box 12 under new code TT. The first W-2s carrying it go out in January 2027.

The number is due whether or not your payroll system can produce it — and for a large class of employers, the obvious shortcut produces the wrong number in a way the IRS has already described in print.

This guide covers what code TT is, exactly which dollars go in it, why the common estimate diverges from the legal number, and what to do between now and January — with worked examples you can check by hand or in the free TT calculator.

No tax on overtime: the employer reporting requirements, and when they bite

The short version: reporting was optional for 2025, is mandatory for tax year 2026, and the penalty relief was not extended.

The One Big Beautiful Bill Act (OBBBA, July 2025) created a federal income-tax deduction for overtime pay — "no tax on overtime" — for tax years 2025 through 2028. Employees can deduct up to $12,500 ($25,000 married filing jointly) of qualified overtime compensation, phasing out above $150,000/$300,000 MAGI (IRS Q&A).

To claim the deduction, an employee needs a number from you. The timeline:

What actually goes in Box TT: less than you think

Qualified overtime compensation is defined in IRC §225(c) as overtime compensation required under section 7 of the FLSA that is in excess of the regular rate (Notice 2025-69 §II.B). The 2026 W-2 instructions put it plainly: code TT reports "the 'and-a-half' portion of time-and-a-half compensation."

Two filters, both narrow:

Filter 1 — premium portion only. For an overtime hour paid at time-and-a-half, only the 0.5× increment above the regular rate counts. The 1.0× straight-time portion is ordinary wages.

Filter 2 — FLSA-required only. Overtime your payroll pays that federal law doesn't compel is excluded:

So the TT number is a federal-law computation over a partition of time (the workweek) that your payroll system does not natively report on. Which brings us to the hard part.

The premium rides on the regular rate of pay — and that's where the number breaks

The FLSA premium is 0.5 × the regular rate of pay — not 0.5 × the hourly wage. The regular rate is recomputed every workweek:

regular rate = all includable remuneration for the workweek ÷ total hours worked that week

"Includable" is broad by design (29 USC §207(e); DOL Fact Sheet #56A): nondiscretionary bonuses (attendance, production, safety, retention — any bonus that's promised or expected), commissions, shift differentials, on-call pay, per diems that function as wages. The eight statutory exclusions are narrow; the default is in.

Worked example (check it in the calculator)

Maria earns $20/hour and works 50 hours in a workweek with a $200 attendance bonus:

Includable pay:      50 × $20 + $200        = $1,200
Regular rate:        $1,200 ÷ 50            = $24.00/hr   (not $20)
FLSA premium:        0.5 × $24.00 × 10 OT h = $120.00     ← this week's code TT dollars
What a bonus-blind
system computes:     0.5 × $20.00 × 10      = $100.00

The system's number is off by $20 — and note carefully what that $20 is. It is simultaneously:

  1. a W-2 reporting error (Box TT understated), and
  2. an overtime underpayment (Maria was owed the premium on $24, not $20 — see the same arithmetic in the regulation's own example at 29 CFR 778.110(b): $12/hr, 46 hours, $46 bonus → $13.00 regular rate).

One computation, two exposures. Multiply by employees and weeks.

"Can't I just divide total overtime by 3?" — read the fine print

You may have heard the IRS blesses estimating the premium as total overtime pay ÷ 3 (an OT line paid at 1.5× is three units of 0.5×, so one-third is the premium). Three things employers need to know about that shortcut, all from Notice 2025-69 itself:

  1. It was employee-side relief. The ÷3 method (the Notice's method (B), example 2) exists so individuals could estimate their own deduction from pay stubs in the transition year when employers weren't reporting.
  2. It was for tax year 2025 only. The Notice's applicability section is one sentence: "This notice applies to the 2025 tax year." The OBBBA's own transition rule (§70202(h)) permits approximation only for periods before January 1, 2026. No equivalent estimate has been blessed for TY2026 employer reporting.
  3. The IRS says when ÷3 is wrong — and it's when you pay bonuses. Method (E) of the Notice concedes that the ÷3 approach "would result in underestimating the employee's qualified overtime compensation (for example, because the individual's regular rate is increased by a nondiscretionary bonus)."

That last point deserves a slow read. ÷3 of the OT line equals the true premium only if every overtime hour was paid at exactly 1.5× a correctly computed regular rate. If your people earn nondiscretionary bonuses, differentials, or commissions and your system pays OT on the base rate, then ÷3 reproduces your system's error — an error the IRS has now described, in a published notice, for a tax document your employees will use to claim deductions.

What used to be invisible payroll rounding is becoming a number on a federal form, cross-checkable by any employee (or any plaintiff's lawyer) who can divide.

The retroactive bonus: the case that breaks batch payroll

Quarterly and annual nondiscretionary bonuses are the worst case. Under 29 CFR 778.209, a bonus earned over multiple workweeks must be allocated back across those workweeks (equal per week, or per hour, so long as the method is "reasonable and equitable"), each week's regular rate recomputed, and the extra half-time paid on each week's overtime hours.

Example: a $1,300 quarterly bonus over 13 weeks for an employee averaging 45 hours/week allocates $100/week, raises each week's regular rate by $100 ÷ 45 ≈ $2.22, and generates 0.5 × $2.22 × 5 ≈ $5.56 of additional premium per week — about $72 of true-up for the quarter, per employee.

Payroll systems process periods forward and close them; almost none replays closed periods when an October bonus lands. If the true-up isn't paid, it isn't in your OT totals — and it isn't in your Box TT number either.

(One structure escapes the replay: a bonus paid as a fixed percentage of total earnings including overtime already embeds the premium, so no retroactive recomputation is required — confirmed in DOL Opinion Letter FLSA2026-6 (2026). Flat-dollar quarterly bonuses, the far more common design, get no such pass.)

California employers: your TT number is smaller and harder

California's overtime rules are broader than the FLSA's, and code TT deliberately ignores the difference:

Practical upshot: a California employer needs the FLSA computation and the California computation as separate, correct layers. A system that blends them will misstate one or the other — TT on the W-2, or wages on the paystub.

What to do before January (a five-step dry run)

  1. Inventory pay codes. List every earning code; mark each as includable in the regular rate or excludable under §207(e). (Almost every bonus your managers would describe as "expected" is includable.)
  2. Ask your payroll vendor, in writing: "Can the system isolate the FLSA-required 0.5× premium, computed on a §207(e)-complete regular rate, separately from state-law and contractual overtime — per workweek?" Get the answer before Q4 close, not in January.
  3. Pick and paper a methodology. Exact computation from workweek data, or a documented method with known limits. Consistency and documentation are the defense; an undocumented shortcut is neither.
  4. Run a TY2026 dry run on real data. Take a quarter of payroll registers and time data, compute the TT figure, and reconcile it against what the system would report. The size of the gap is the size of the January problem — and of the underlying wage exposure.
  5. Track guidance monthly. The IRS could still extend relief (as of July 2026 it has not; the 2026 W-2 instructions are final). If relief comes, the reporting pressure eases — the wage-and-hour liability underneath does not move an inch.

The uncomfortable conclusion

Computing Box TT correctly requires computing the regular rate correctly — and the regular rate is simultaneously the basis of overtime pay itself, California meal and rest premiums, and the penalty stack PAGA attaches to all of it. An employer who builds the TT number properly has, as a byproduct, audited its own overtime compliance.

An employer who ships an estimate has put a checkable number on a federal tax form and left the underlying error in place — documented, now, by the IRS's own description of when the estimate fails.

The reporting mandate and the liability question are the same computation. You might as well get the audit for free.

Run one week of your own numbers in the TT calculator — or request a free exposure snapshot: I run the full computation on a quarter of your actual payroll register and punch data and show you the gap, employee by employee, pay code by pay code. Request a snapshot →

FAQ

What is W-2 Box 12 code TT? The W-2 field, mandatory starting tax year 2026, where employers report an employee's total qualified overtime compensation — the premium ("half") portion of FLSA-required time-and-a-half — which employees use to claim the OBBBA overtime deduction (2026 W-2/W-3 instructions).

Is all overtime pay reported under code TT? No. Only the 0.5× premium of overtime the FLSA itself requires (over 40 hours/workweek). Straight-time portions, state-law-only overtime (e.g., California daily OT in a sub-40 week), the extra half of California double time, and contractual overtime are excluded.

Can employers report an estimate (total OT ÷ 3) for 2026? The ÷3 method in Notice 2025-69 was guidance for employees, for tax year 2025 only. No estimation method has been blessed for TY2026 employer W-2 reporting, and the Notice itself states ÷3 underestimates the true amount when a nondiscretionary bonus raises the regular rate.

What happens if the Box TT amount is wrong? Information-return penalties under IRC §§6721/6722 can apply (up to $330 per form; more for intentional disregard). Separately, if the number is wrong because the regular rate is wrong, the same error usually means overtime was underpaid — a wage-and-hour exposure with a 2–3 year federal (4-year California) lookback.

Do bonuses really change the overtime rate? Nondiscretionary bonuses — anything promised or expected, like attendance or production bonuses — must be included in the regular rate before the overtime premium is computed (29 CFR 778.110(b); DOL Fact Sheet #56C; DOL Opinion Letter FLSA2026-2, Jan. 5, 2026, with its own worked example: $12/hr + $9.50/hr in incentive bonuses over 50 hours → $21.50 regular rate). A $200 weekly bonus for an employee at $20/hr working 50 hours raises the regular rate to $24 and the week's premium by $20.

Does code TT apply to salaried-exempt employees? No — overtime paid to FLSA-exempt employees is not qualified overtime compensation, regardless of state law or employer policy.

Sources: IRS Q&A: qualified overtime deduction · IRS Notice 2025-69 · IRS Notice 2025-62 (IRB 2025-48) · 2026 General Instructions for Forms W-2/W-3 · DOL Fact Sheet #56A · DOL Fact Sheet #56C · DOL Opinion Letter FLSA2026-2 (Jan. 5, 2026) · DOL Opinion Letter FLSA2026-6 (2026) · 29 CFR 778.110 · 29 CFR 778.209 · Ferra v. Loews Hollywood Hotel, 11 Cal.5th 858 (2021) · Alvarado v. Dart Container, 4 Cal.5th 542 (2018)

Not legal or tax advice. Written by an engineer who builds the computation; methodology and test cases are public. Attorney review pending — this page will carry the reviewer's byline when it does.