How Changing Jobs Midyear Can Affect Your Taxes
- Lydia Desnoyers
- 2 days ago
- 8 min read
Changing jobs midyear can create a withholding gap many people do not discover until they file. Each employer withholds based on the W-4 on file and the wages it pays through its own payroll system. Your new employer usually does not know what you earned earlier in the year, how much was already withheld, or whether severance, bonus income, side income, or spouse income changed your full-year tax picture.
With two W-2s on the same return, the total withholding may be less than the tax owed on the combined income. A midyear review of your W-4 and estimated payment obligations can close that gap before it becomes a filing-season surprise. The IRS Tax Withholding Estimator is the starting point, and a conversation with a CPA can help you model the full picture.
Key Takeaways
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Why Two Employers in One Year Can Create a Withholding Gap
Federal income tax is progressive. The more you earn in a year, the higher the rate applied to the top portion of your income. Each employer's payroll system calculates withholding based on the wages it pays and the W-4 information on file, without visibility into your total annual earnings from all sources.
If you earned $50,000 at your first job before June and then earned $70,000 at your new job during the rest of the year, your tax return reflects $120,000 of wage income. Each employer only sees the wages it paid and the W-4 information on file. Neither payroll system automatically accounts for the full income from both jobs.
The result can be a shortfall. The tax calculated on $120,000 of combined income may be higher than the total amount both employers withheld on their respective shares.
Tip: Run the IRS Tax Withholding Estimator after starting a new position. Input your year-to-date earnings from your prior W-2 alongside your projected earnings at the new job. The tool can identify a shortfall before filing season.
What to Adjust on Your W-4 at the New Job
The W-4 you complete when starting a new position is one of the main ways to adjust future withholding. During onboarding, it is easy to focus on the new role and move through the tax form quickly. The problem is that the W-4 affects how much federal tax is withheld from each paycheck, and the new employer usually does not know what has already happened earlier in the year.
Before submitting the form, review year-to-date wages, prior withholding, severance, bonus income, side income, and spouse income. Those numbers help determine whether the default W-4 calculation is enough or whether an additional amount should be withheld from each paycheck.
The current W-4 includes a section for people with more than one job or for spouses who also work. You can use the IRS estimator for a specific additional withholding amount, complete the Multiple Jobs Worksheet on the form, or check the box indicating two jobs.
The checkbox method is simple, but less precise. It uses a standard calculation that may still leave a gap depending on the income split between positions.
Requesting a specific additional dollar amount withheld per paycheck, entered on Line 4c of the W-4, can be more precise than relying on the standard calculation. A CPA can calculate this figure based on actual year-to-date income, projected remaining income, and current withholding totals.
The timing also matters. A W-4 adjustment at the new job only affects future paychecks. If you start the new position in September, there are fewer remaining paychecks to absorb the correction. The later in the year the job change occurs, the larger the per-paycheck adjustment may need to be.
How Severance, PTO Payouts, and Signing Bonuses Affect Withholding
A severance payment from your former employer and a signing bonus from your new employer can both land in the same tax year. The IRS classifies these lump-sum payments as supplemental wages, and federal withholding on supplemental income is typically a flat 22%.
That 22% is the withholding rate, not your final tax rate. If your combined annual income pushes part of your earnings into the 24% or 32% bracket, the flat rate falls short of what you owe.
Here is what that gap looks like on a $15,000 severance check for someone in the 32% bracket:
Withheld at 22%: $3,300
Actual tax owed at 32%: $4,800
Shortfall at filing: $1,500
Unused PTO payouts follow the same supplemental wage rules. A PTO cash-out from your old employer and a signing bonus from the new one in the same quarter means the under-withholding compounds quickly.
Tip: If you receive a severance or signing bonus, ask your CPA to recalculate your W-4 withholding at the new employer to account for the lump-sum income. You can also make a one-time estimated tax payment to cover the gap rather than adjusting every paycheck.
Side Business or 1099 Income During a Job Transition
People who freelance, consult, or run a side business while changing W-2 jobs face a more complex calculation. Self-employment income is subject to both income tax and self-employment tax (15.3% on net earnings up to the Social Security wage base, with the 2.9% Medicare portion applying to all net self-employment income).
When W-2 withholding from the new employer no longer covers the combined liability from wages plus self-employment earnings, the IRS expects quarterly estimated payments. Estimated payments may be required if you expect to owe at least $1,000 after subtracting withholding and refundable credits and you do not meet one of the IRS safe harbor rules. Missing those payments can trigger a quarterly underpayment penalty.
The job change makes this harder to manage because the withholding that previously offset some of your self-employment exposure may be lower at the new employer. If your new W-4 does not account for both the W-2 gap and the 1099 income, the shortfall compounds.
Earners whose combined W-2 and self-employment income exceeds $200,000 (single) or $250,000 (married filing jointly) should also factor in the Additional Medicare Tax of 0.9%, which applies to earned income above those thresholds. This tax is reported on Form 8959 and is not withheld by employers unless W-2 wages alone exceed $200,000.
Tip: If you have both W-2 and 1099 income during a job transition year, ask your CPA to review both income sources together. The review can show whether you need to increase W-4 withholding, make estimated tax payments, or use a mix of both. Reviewing both at the same time reduces the risk of underpaying in one area while overcorrecting in another.
Retirement Plan Decisions That Can Create Taxable Events
Withholding is not the only tax issue that arises from a job change. Retirement plan decisions can also affect taxable income for the year.
Leaving an employer with a 401(k) balance creates a decision point with direct tax consequences. You have four options:
Leave the balance in the former employer's plan
Roll it into the new employer's plan
Roll it into an IRA
Cash it out
Cashing out triggers income tax on the full distribution, plus a possible 10% additional tax if you are under age 59½ and no exception applies. On a $40,000 cash-out in the 24% bracket, that means roughly $9,600 in income tax and a $4,000 penalty, leaving $26,400 before state taxes.
Rollovers avoid the immediate tax hit, but the method matters:
Direct rollover (trustee-to-trustee transfer): The cleanest option. Funds move between accounts, and nothing is withheld.
Indirect rollover: Funds are distributed to you, and you have 60 days to deposit them into a qualifying account. The former plan requires withholding 20% for federal taxes. If you do not replace that 20% from other funds when making the deposit, the withheld amount is treated as a taxable distribution.
These decisions should be made with a clear understanding of the tax consequences, not based on which option feels most convenient during the transition. A review of the IRS rules on lump-sum distributions is a good starting point.
When a Job Change Should Prompt a Tax Planning Conversation
A midyear job change is among events like marriage, divorce, or starting a business that serve as tax-planning triggers. The income shift, benefit changes, and retirement plan decisions create enough variables that a brief review with a CPA during the transition can prevent problems that are harder to fix at the time of filing.
This is especially true if your situation includes any of the following: severance or signing bonus income, self-employment or 1099 income alongside the new W-2 position, a significant salary increase, or a retirement plan balance that needs to be moved.
A CPA review after a job change can compare your year-to-date wages, federal withholding, state withholding, severance, bonus income, side income, and retirement plan decisions. From there, the review can indicate whether a W-4 adjustment, an estimated payment, or a rollover planning step is needed before the filing season.
Tax planning during a job change is about reviewing the numbers while adjustments are still possible. Waiting until January to gather your W-2s and hoping the withholding worked out is the pattern that leads to unexpected balances due.
If you changed jobs this year and want to review your withholding, estimated tax payments, or retirement plan decisions before filing season, schedule a consultation with our team.
Do two W-2s mean I get taxed twice on my income?
Two W-2s do not mean double taxation. Your total income is taxed once based on the combined amount. The issue is that each employer withheld independently based on its own payroll data, so the combined withholding may fall short of the tax owed on your total earnings.
Should I update my W-4 at my new job even if the salary is similar?
In many cases, yes. Even if the salary is comparable, the new employer does not know about the income you already earned earlier in the year. Completing the W-4 with your year-to-date earnings in mind, or requesting a specific additional withholding amount, helps close the gap.
I received severance and started a new job the same month. Will I owe more at filing?
It depends on the amounts and your overall tax picture. Severance is typically withheld at the 22% supplemental rate, which may be lower than your marginal tax rate when combined with your new salary. The gap between what was withheld from your severance and the rate applied to your total income can create an additional balance due.
How do I know if I need to make estimated tax payments after a job change?
Estimated payments may be required if you expect to owe at least $1,000 after subtracting withholding and refundable credits and you do not meet one of the IRS safe harbor rules. This is most common when self-employment income is combined with W-2 wages. The IRS estimated tax page explains the safe harbor rules and payment deadlines.
What happens if I cash out my old 401(k) during a job transition?
The full distribution is treated as taxable income in the year you receive it. If you are under age 59½, a 10% additional tax may apply unless an exception applies. The combination of the distribution, your W-2 income from both jobs, and any other earnings can push you into a higher bracket than expected.
About the author
Lydia Desnoyers, CPA is a Business Advisor and Fractional CFO at DesCPA. She works with business owners and women-led law firms on financial strategy, cash flow planning, and tax planning decisions that support long-term growth.
Her writing focuses on practical guidance that helps readers understand when numbers are accurate, when strategy matters, and how to make better financial decisions with the information they already have.
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