Starting a Job Mid-Year: Why Withholding Overshoots

By GetTaxCalculator Editorial Team· Published 2026-09-12

When you start a new job mid-year, your employer's payroll system annualizes your income from Day 1 - which means it assumes you will earn that same amount for a full 12 months. If you start in July earning $40,000 per year, the system withholds as if you will earn $40,000 for the year, but you will actually only earn about $20,000 for the remaining 6 months. This causes over-withholding and almost always results in a refund when you file your return.

How payroll annualization works

Federal income tax withholding is designed to collect roughly the right amount of tax over a full year. To accomplish this, the IRS requires employers to use an annualization method when calculating withholding:

Take your per-paycheck gross pay.
Multiply it by the number of pay periods in a year (26 for biweekly, 24 for semimonthly, 52 for weekly).
That projected annual income determines which tax bracket applies and how much to withhold each period.

This works well when you work the entire year. If you earn $40,000 total over 52 weeks, annualizing any individual paycheck arrives at $40,000 per year - which is accurate. But if you only work 26 weeks of the year at that same rate, annualizing gives $40,000 when your actual year-end income will be $20,000. The system withholds too much because it does not know you started mid-year.

Why mid-year means over-withholding

The over-withholding happens because the annualized income (what the system thinks you will earn) is higher than your actual annual income. A higher projected income means a higher tax bracket applies, which means more is withheld per paycheck.

The 2026 single-filer brackets illustrate the effect:

10% on taxable income from $0 to $12,400
12% on taxable income from $12,400 to $50,400
22% on taxable income from $50,400 to $105,700

A taxpayer the payroll system assumes will earn $40,000 per year has a taxable income (after the $16,100 standard deduction) of $23,900. A taxpayer who will actually earn $20,000 has taxable income of $3,900. Those two taxpayers have very different effective withholding rates, even though they get the same paycheck.

Worked example: $40K salary, start July 1

Here is a concrete example using 2026 figures:

Annual salary rate: $40,000
Start date: July 1 (approximately 6 months remaining)
Actual 2026 earnings: approximately $20,000
What payroll assumes: $40,000 full-year income

Tax on the assumed $40,000 (taxable income $23,900 after the $16,100 standard deduction):

First $12,400 at 10% = $1,240.00
Remaining $11,500 at 12% = $1,380.00
Total assumed annual tax = $2,620.00

Tax on the actual $20,000 (taxable income $3,900 after the $16,100 standard deduction):

$3,900 at 10% = $390.00
Total actual annual tax = $390.00

The difference - approximately $2,230.00 - is the amount over-withheld for the year due to the annualization effect. This comes back as a federal refund when you file your return in early 2027.

How to fix it

If you would rather have the extra money in your paychecks now instead of as a refund later, you can adjust your W-4:

Step 4(b) - Deductions: Enter an amount larger than the standard deduction here. The payroll system will treat that extra amount as a deduction, reducing your projected taxable income and therefore your withholding. This is the most common approach.
Step 4(c) - Extra withholding: This step adds to withholding, not reduces it. Do not use this step to solve over-withholding.

To calculate how much to enter in Step 4(b), use the IRS Tax Withholding Estimator at irs.gov/W4app. Enter your start date and actual expected income for the year, and it will recommend the right W-4 settings.

Note: If you are only a few months from year-end when you start your job, adjusting the W-4 may not be worth the effort. A small change in the remaining paychecks will not recover much, and the refund arrives a few months later anyway.

When to just wait for the refund

For most mid-year starters, the simplest approach is to do nothing and file for the refund in early 2027. This makes sense when:

You started in October, November, or December (too few paychecks left to meaningfully adjust)
The over-withholding amount is modest and the paperwork is not worth it
You are not sure of your year-end income (other income, job changes, bonuses)

The downside of waiting is that the IRS holds your money interest-free until your refund is processed. If you consistently start jobs mid-year and consistently over-withhold, the W-4 adjustment is worth learning once - it applies every time.

Frequently Asked Questions

Why is so much federal tax being taken out of my first few paychecks?

Your employer's payroll system assumes you will earn the same amount for the entire year. If you started mid-year, it annualizes your per-paycheck earnings to project a full-year income, which may land you in a higher tax bracket than your actual part-year earnings justify. This causes more withholding than you ultimately owe.

Will I get a big refund if I started my job mid-year?

Very likely yes - assuming you had no other significant income earlier in the year. If you earned $20,000 in the second half of the year and your employer withheld based on a $40,000 annual salary, you will receive a refund for the difference when you file your return.

How do I use Step 4(b) to reduce over-withholding?

Step 4(b) of the W-4 lets you enter deductions that exceed the standard deduction. If you add an amount here, your employer reduces withholding by that extra deduction each pay period. However, for mid-year over-withholding, the easier fix is often to simply wait for the refund rather than try to fine-tune withholding for the remaining months of the year.

Does starting mid-year affect state income tax withholding too?

Yes, most states use the same annualization approach for state income tax withholding. The same over-withholding effect applies at the state level. You will typically see a state refund as well when you file your state return.

What if I also had a job earlier in the year?

If you had another job earlier in the year, your new employer does not know about that income. You may actually be under-withheld overall because your combined income is higher than either employer assumes. Use Step 2 of the W-4 (multiple jobs checkbox or worksheet) to account for both jobs.

Does the mid-year annualization problem affect FICA taxes?

No. FICA taxes (Social Security and Medicare) are flat-rate taxes on each paycheck and are not affected by annualization. You pay exactly 6.2% Social Security and 1.5% Medicare on each paycheck regardless of when in the year you started.