{
 "task_id": "T06",
 "run": 1,
 "prompt": "A raise was approved six weeks late. Compute retro pay across three periods with a 401(k) deferral.",
 "system": "You are a payroll assistant at a US company. Answer the request.",
 "model": "claude-opus-5-5",
 "response": "# Retro Pay Calculation: Three Pay Periods with 401(k) Deferral\n\nYou didn't include employee details, so this example uses **sample assumptions**. Send me the actual rates, hours, plan terms, and state, and I'll rerun it.\n\n## Assumptions\n\n| Item | Value |\n|---|---|\n| Pay frequency | Biweekly |\n| Old rate | $30.00/hr |\n| New rate (effective 6 weeks ago) | $32.50/hr |\n| Rate difference | $2.50/hr ($3.75/hr overtime) |\n| 401(k) election | 6% traditional pre-tax |\n| Employer match | 100% up to 4% of pay |\n| Federal withholding | 22% flat supplemental rate (retro paid as a separately identified amount) |\n| State | Example 5% flat, and the state excludes 401(k) deferrals from taxable wages |\n| Employee status | Non-exempt, under the Social Security wage base, under $200K YTD |\n\n## Step 1: Gross Retro Pay by Period\n\n| Period | Hours | Calculation | Retro Due |\n|---|---|---|---|\n| 1 | 80 regular | 80 \u00d7 $2.50 | $200.00 |\n| 2 | 80 regular + 6 OT | (80 \u00d7 $2.50) + (6 \u00d7 $3.75) | $222.50 |\n| 3 | 72 regular + 8 PTO | 80 \u00d7 $2.50 | $200.00 |\n| **Total** | | | **$622.50** |\n\nPTO is retro'd because it was paid at the base rate. Overtime must be recalculated at 1.5\u00d7 the new rate under FLSA.\n\n## Step 2: 401(k) Deferral\n\n- Employee deferral: $622.50 \u00d7 6% = **$37.35**\n- Employer match: $622.50 \u00d7 4% = **$24.90**\n\nThis assumes the plan's definition of compensation includes retro pay. Most plans do, but check the plan document.\n\n## Step 3: Taxes\n\n| Item | Taxable Wages | Rate | Amount |\n|---|---|---|---|\n| Federal income tax | $585.15 (gross minus 401(k)) | 22% | $128.73 |\n| Social Security | $622.50 (401(k) not excluded) | 6.2% | $38.60 |\n| Medicare | $622.50 | 1.45% | $9.03 |\n| State income tax | $585.15 | 5% | $29.26 |\n\n## Step 4: Net Retro Pay\n\n| | Amount |\n|---|---|\n| Gross retro | $622.50 |\n| 401(k) deferral | \u2212$37.35 |\n| Federal income tax | \u2212$128.73 |\n| Social Security | \u2212$38.60 |\n| Medicare | \u2212$9.03 |\n| State tax | \u2212$29.26 |\n| **Net to employee** | **$379.53** |\n\nEmployer cost: $622.50 gross + $47.63 employer FICA + $24.90 match, plus FUTA/SUTA if the employee is under those wage bases.\n\n## Compliance Checklist\n\n1. **Tax year:** Retro pay is taxed in the year it's *paid*, not the year it was earned.\n2. **Withholding method:** If retro is combined with regular wages and not separately identified, use the aggregate method instead of the 22% flat rate.\n3. **402(g) limit:** Make sure the deferral doesn't push the employee over the annual limit ($23,500 for 2025, plus catch-up if age 50+).\n4. **State rules:** Some states, such as Pennsylvania, tax 401(k) deferrals. Some states also set deadlines for paying wage adjustments.\n5. **Pay-based deductions:** Recalculate anything tied to pay, such as supplemental life, disability, or garnishments. Flat-dollar health premiums don't change.\n6. **W-2 reporting:** Box 1 excludes the deferral, Boxes 3 and 5 include it, and Box 12 Code D shows $37.35.\n7. **Documentation:** Keep the approval date, effective date, and calculation on file.\n\nIf you send the real figures (salaried or hourly, old and new rates, hours per period, deferral type and percentage, match formula, state, and YTD wages), I'll produce the exact amounts.",
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