January W-4 Calculator
For annual W-4 planning.
The short answer: At the scenario numbers pre-loaded below, the OBBBA deductions total $8,220, worth about $986 in federal income tax at a 12% marginal rate ($38 per biweekly paycheck) — that's the gap your W-4 can capture during the year.
⚠️ This calculator provides estimates for informational and educational purposes only. It is not tax advice. Results are based on the One Big Beautiful Bill Act (OBBBA) and IRS Schedule 1-A. Consult a qualified tax professional for your specific situation.
Withholding vs. What You Actually Owe
January is the one moment the full-year picture is visible — set 4(b) once and let it ride.
- • Project annual OT hours, tips, interest, senior bonus
- • One 4(b) entry, twelve months of bigger checks
- • Mid-year course-correct only on surprises
Worked Example
A worker planning a full year of OT and a car loan.
- • Total OBBBA deductions: $8,220
- • Federal income tax savings: $986 at the 12% marginal rate
- • Per biweekly paycheck: $38 — capture it via a W-4 4(b) adjustment instead of waiting for refund season
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Frequently Asked Questions
When's the best time to update the W-4?
January — project the year's deductions once and capture them across all 26 paychecks.
What if my January estimate is wrong?
File a new W-4 anytime; per-paycheck effects are immediate.