Blog · 16 October 2026

Box 12 Code TT Qualified Overtime: Why It Will Not Tie to the Payroll Register for US CPA Firms

By Keshav Bansal, CA

For 2026 Forms W-2, Box 12, code TT does not report the overtime line on the payroll register. It reports qualified overtime compensation under IRC §225(c)(1)—only the Fair Labor Standards Act (FLSA) section 7 half-time premium for hours over 40, not the full overtime earning. CPA Practice Advisor (Aeon Aurora, Oct. 13, 2026) explains why the two numbers often will not tie. US CPA firms that reconcile “OT paid” to Box 12 TT without the IRS formula will mis-build Schedule 1-A and misstate the above-the-line deduction.

What code TT reports

Under 26 U.S.C. §225(c)(1), “qualified overtime compensation” means overtime compensation paid to an individual that is required under section 7 of the Fair Labor Standards Act of 1938 and that is in excess of the regular rate (as used in that section). Two limits sit in that sentence: only what the FLSA required, and only the part above the regular rate. IRS FS-2026-13 (August 2026) restates the same idea: overtime compensation not required by the FLSA is not eligible for the deduction (Q1). Starting in tax year 2026, employers must separately report the amount on Form W-2 in box 12 using code TT (FS-2026-13 Q6 and Q10). CPA Practice Advisor notes that the 2026 General Instructions for Forms W-2 and W-3 put it plainly: only the “half” portion of “time-and-a-half” compensation is reported using code TT.

The FS-2026-13 Q12 formula

FS-2026-13 Question 12 gives the employer computation for most employees: number of FLSA hours worked in excess of 40 in a workweek × one-half × the employee’s FLSA regular rate of pay = qualified overtime compensation for that workweek. A workweek is a fixed and regularly recurring period of 168 hours—seven consecutive 24-hour periods—and each workweek stands alone; hours may not be averaged over two or more workweeks (Q13).

For the easy case—time-and-a-half on a single hourly rate for hours over 40, with no other pay in the week—the arithmetic is a division. CPA Practice Advisor’s example: overtime earnings of $4,812 carry $1,604 of code TT (one-third). That is the only case where the register and the box agree once the overtime line is divided by three.

When the register and Box 12 diverge

FS-2026-13 Q16 works a double-time example. An employee at $20 an hour works 50 hours and the employer pays two times the regular rate for the 10 overtime hours ($400 for those hours). Section 7 required $300 ($200 of straight time plus $100 of premium at half the regular rate). Code TT is $100. The other $100 is overtime the FLSA did not require and is not qualified.

Aurora’s article and the fact sheet also flag common mismatches:

• Daily, weekend, or holiday premiums with no hours over 40. Premiums for hours the FLSA does not treat as overtime count only to the extent credited toward the section 7 obligation (Q16). A four-day week of 10-hour days under a daily overtime rule can produce daily premium with zero hours over 40—and nothing to report under Q12.
• Paid hours that are not hours worked. Holiday, vacation, or sick pay is generally not compensation for hours of employment for FLSA overtime purposes; a payroll that pays “overtime” after 40 paid hours can show register premium where code TT is zero (CPA Practice Advisor, citing FS Q14).
• Pay period versus workweek. A semi-monthly register may never show 40 hours in either half of a week that still has overtime when hours are totaled by workweek (Q13).
• Regular-rate inputs. Shift differentials and nondiscretionary bonuses raise the FLSA regular rate (Q15; 29 U.S.C. §207(e)), so a premium computed only on the base hourly rate can understate code TT.

What the employee may deduct

Section 225(a) allows a deduction equal to the qualified overtime compensation received during the year and included on the required statements (including Form W-2 reporting under §6051(a)(19)). The deduction is limited to $12,500 ($25,000 on a joint return) and is reduced by $100 for each $1,000 by which modified AGI exceeds $150,000 ($300,000 joint) under §225(b). FS-2026-13 Q2 matches those caps and MAGI thresholds. A Social Security number is required; married individuals must file jointly (§225(d)–(e)). No deduction is allowed for taxable years beginning after December 31, 2028 (§225(g)).

FS-2026-13 Q19 is the return-side rule: Box 12, code TT is the starting point on Schedule 1-A (Form 1040) Part III; the schedule then applies the annual cap and MAGI reduction. The employer must still report the full qualified amount even when it exceeds the employee’s deduction limit—Q10’s example reports $30,000 in code TT even though the ceiling is $12,500 / $25,000. Our Schedule 1-A senior-deduction article covers how the four Additional Deductions total to Form 1040 line 13b; overtime itself is Part III, not Part V.

W-2c, not Form 4852—and no 2025 approximate shortcuts

If Box 12, code TT is wrong, the employer must file Form W-2c with SSA and furnish it to the employee as soon as possible (FS-2026-13 Q11). After 2025, employees may not claim qualified overtime above what Box 12 TT shows (Q20). Notice 2025-69 provided relief for the 2025 tax year only; FS-2026-13 states that no such relief is available for tax years after 2025. If the employer overstates TT, the employee may use only the actual qualified amount (Q21). If TT is omitted or understated, the employee must request a W-2c; Form 4852 (substitute W-2) does not satisfy the statement requirement in §225(a), so amounts on Form 4852 cannot be used to compute the deduction (Q22–Q23).

Withholding conversations belong on the W-4 side—see our draft 2027 Form W-4 OBBBA overview—but return prep still starts from the corrected Box 12 TT figure. Related employer reporting for tips and overtime also appears on the revised Form 1099-NEC/MISC rules in our Form 1099-NEC $2,000 threshold article.

CPA checklist for Box 12, code TT

1. Do not equate register OT to code TT. Recompute from FLSA hours over 40 × ½ × regular rate (FS-2026-13 Q12).
2. Confirm FLSA overtime-eligible status. Exempt employees do not receive qualified overtime for this deduction (Q4).
3. Strip non-FLSA premiums. Double time, daily OT with ≤40 hours in the week, and similar extras count only to the FLSA-required half (Q16).
4. Use workweeks, not pay periods, and FLSA hours worked, not merely hours paid (Q13–Q14).
5. Rebuild the regular rate when bonuses or shift differentials apply (Q15).
6. Report the full TT amount on the W-2 even if it exceeds the employee’s $12,500 / $25,000 cap (Q10).
7. Correct errors with Form W-2c. Do not coach clients to “fix” TT on Form 4852 (Q11, Q22–Q23).
8. On Schedule 1-A, start from Box 12 TT, then apply the annual limit and MAGI phaseout (§225(b); Q19).
9. Calendar the 2028 sunset and coordinate withholding estimates that assume permanent OT relief (§225(g)).

Where Tax Brew fits

Box 12 TT review is a payroll-to-return control: timekeeping extracts, regular-rate workpapers, and W-2c follow-up. Tax Brew supports US CPA firms with tax prep support, bookkeeping and cleanup so reviewers can spend more time on FLSA eligibility and Schedule 1-A judgment calls. The first 20 hours are free for qualifying engagements. See our services, or email info@taxbrewglobal.com.

Sources: IRS FS-2026-13, No Tax on Overtime Q&As (Aug. 6, 2026 update), especially Q1–Q2, Q6, Q10–Q16, Q19–Q23; 26 U.S.C. §225 (Cornell LII); CPA Practice Advisor, Aeon Aurora, “When Box 12, Code TT Will Not Tie to the Payroll Register” (Oct. 13, 2026), citing the 2026 General Instructions for Forms W-2 and W-3 and FS-2026-13. General information, not tax or legal advice. As of 16 October 2026.