The situation in the calculator
The page opens with someone who has just started a new job paying $2,600 every two weeks, with nothing from it paid or withheld yet. Earlier this year they earned $31,000 at their old job, which withheld $3,100 of federal income tax. The calculator counts the new job’s paychecks left in 2026, adds the old job’s pay and withholding, and projects the year’s tax for a single filer.
The new employer’s tables see $2,600 every two weeks and withhold as if that were $67,600 for the whole year. Whether that ends in a refund or a bill depends on the months before: a gap between jobs usually means too much withheld, a well-paid old job with low withholding can mean too little. The hero figure tells you which, and the suggested W-4 spreads the difference over the new job’s remaining paychecks.
Filling in the new W-4
- Type the paychecks left this year at the new job, and your taxable pay per paycheck (pay minus pre-tax 401(k) and health deductions).
- Under Other jobs and income, enter the old job’s year-to-date taxable pay and federal tax withheld from its last stub.
- Add other income, deductions and children if you have them, then copy the suggested Steps 3, 4(a), 4(b) and 4(c) onto the new W-4.
If your employer offers the part-year method in Publication 15-T, it handles a short first year automatically, but it needs a written request with the dates of your previous job. The W-4 route works with any payroll.
Next January
The suggestion is sized for the paychecks left in 2026. In January the new job will be your only income for the whole year, so give your employer a fresh W-4 for 2027: usually just your filing status, plus Step 3 for children and Step 4 for other income or deductions.