Starting a job midyear
Why is the first paycheck smaller after a midyear start?
First check the days or hours included and the payroll cutoff. A partial payment can be smaller than the normal installment even when the salary is correct. Regular withholding uses the payroll frequency, not simply the number of checks you have left this year.
This hypothetical example assumes ordinary 2026 Texas wages, a single filer with a current W-4, Step 2 unchecked and Steps 3-4 blank, no earlier wages, no deductions and no special withholding method. It does not establish a legally required salary-proration formula or payday.
Get the first payment's coverage in writing
Ask payroll for the first pay date, the period's start and end dates, the cutoff for including your time, and the gross amount expected. A start date and an annual salary alone do not show whether the first deposit covers a full period. Also confirm when insurance and retirement deductions begin; the second check can differ even after gross pay becomes regular.
A confirmed $1,500 partial payment at a $78,000 salary
Assume the employer confirms $1,500 for the first partial biweekly period, followed by normal $3,000 payments. The $1,500 is an agreed example input, not a claim that every employer must prorate this way. Publication 15 uses the regular payroll period for withholding even when an employee works only part of it.
| Payment line | Partial first check | Normal later check |
|---|---|---|
| Gross cash pay | $1,500.00 | $3,000.00 |
| Federal income tax withheld | $96.15 | $320.38 |
| Social Security withheld | $93.00 | $186.00 |
| Medicare withheld | $21.75 | $43.50 |
| Net payment | $1,289.10 | $2,450.12 |
For the first check, $1,500 x 26 = $39,000 annualized wages. Worksheet 1A yields $2,500 tentative annual withholding; $2,500 / 26 rounds to $96.15. The normal payment produces $320.38. Half the gross therefore does not mean half the income-tax withholding, and $1,289.10 is not half of $2,450.12.
Reproduce only the $1,500 partial payment. This tool accepts annual salary rather than current gross, so $39,000 is a temporary equivalent input that makes it calculate $1,500 over 26 periods. It is neither the employment offer nor expected annual earnings. Use $78,000 for the normal later payment.
Make a separate calendar-year cash projection
Suppose payroll confirms that eleven full payments will follow the partial payment before December 31. This job then pays $1,500 + 11 x $3,000 = $34,500 during the year, not $78,000 and not the first check's $39,000 annualization. With unchanged inputs and cent-rounded withholding on each check, federal withholding totals $96.15 + 11 x $320.38 = $3,620.33.
That is a withholding forecast, not final income tax or a promised refund. Add any earlier employer's wages and withholding, other income and household circumstances to a separate annual review. Keep actual payment dates in the projection, including wages for late-December work that are paid in January.
Choose a withholding review, not an invented pay frequency
Use the IRS Tax Withholding Estimator with recent pay stubs, prior income and expected remaining pay. Include a spouse's income for a joint-return estimate. Recheck a midyear W-4 adjustment when the next full year starts. Do not lower the salary input to $34,500 to model the normal check, or replace 26 with twelve merely because twelve payments will occur this year.
Publication 15-T also describes a separate part-year method. A calendar-year taxpayer expecting no more than 245 days of continuous employment across all employers can ask payroll about it. The written request, under penalties of perjury, must include prior employment's last day and the required calendar-year and employment statements. Eligibility is not automatic from a late start; confirm payroll's handling. The calculator does not implement that alternative method.
Common first-check mistakes
- Disputing withholding before checking whether some work falls after the first cutoff.
- Using an annual earnings forecast as the calculator's annualized salary for one regular payment.
- Assuming no prior wages means no current Social Security or Medicare withholding.
- Carrying forward a temporary W-4 adjustment without reviewing next year's full-year income.
A signing bonus, relocation payment, old W-4, nonresident tax status or irregular payroll period needs a separate analysis. The ordinary first-check example does not model those cases.
Sources checked September 7, 2026: 2026 IRS Publication 15, section 8, 2026 IRS Publication 15-T, Worksheet 1A and section 6 part-year employment, and IRS Tax Withholding Estimator. All payment amounts and the remaining-check count are hypothetical.