Job Change Tax Differences: What You Need to Know When Switching Employers

By Daniel Kim, EA | Published: July 19, 2026 | Updated: July 19, 2026

Key Topics: Job Change Tax, W-4 Form, Tax Withholding, 401(k) Rollover, Unemployment Benefits, Severance Pay, COBRA, Relocation Expenses, Social Security, Medicare

Changing jobs is exciting—new opportunities, better pay, maybe even a fresh start. But between the excitement and the to-do list, there’s one thing you shouldn’t forget: taxes. Switching employers can mess with your withholding, your 401(k), and even your unemployment benefits if you have a gap. Let’s make sure you don’t get caught off guard.

First Things First: The W-4 Form

When you start a new job, you’ll need to fill out a new W-4 form. This form tells your employer how much tax to withhold from your paycheck. The new W-4 is simpler than the old version, but it’s still important to fill it out correctly.

What’s Changed on the New W-4?

The 2020 W-4 eliminated allowances and instead uses a more straightforward approach:

• Your filing status (single, married filing jointly, etc.)
• Whether you have multiple jobs or your spouse works
• Your dependents
• Any additional income (like investments or side gigs)
• Any additional withholding you want

Why Getting the W-4 Right Matters

If you withhold too little, you’ll owe money when you file your tax return—and possibly face underpayment penalties. If you withhold too much, you’ll get a refund, but that means you’ve been giving the government an interest-free loan.

Use the IRS Tax Withholding Estimator to help you fill out your W-4 correctly. Our Salary After Tax Calculator can also help you estimate your take-home pay with your new salary.

Tax Withholding When Changing Jobs

When you switch jobs, your withholding can change for several reasons:

1. Different Salary

If your new salary is higher or lower than your old one, your withholding will adjust accordingly. Higher pay means higher taxes (since you’re in a higher tax bracket), and lower pay means lower taxes.

2. Different Pay Schedule

Your old job might have paid you weekly, while your new job pays biweekly or monthly. This affects how much tax is withheld each pay period.

3. Multiple Jobs

If you’re working two jobs at the same time (maybe your old job overlaps with your new one), each employer will withhold taxes as if you only have that one job. This can result in underwithholding. Use the W-4’s multiple jobs worksheet to adjust your withholding.

4. Benefits Changes

Your new job might offer different benefits—health insurance, 401(k), flexible spending accounts—that affect your taxable income.

What Happens to Your Old 401(k)?

When you leave a job, you have several options for your old 401(k):

Option 1: Roll Over to Your New Employer’s Plan

This is usually the easiest option. Your new employer can help you transfer the money directly from your old 401(k) to your new one. This is a “direct rollover” and avoids any taxes or penalties.

Option 2: Roll Over to an IRA

You can also roll over your 401(k) to an IRA. This gives you more control over your investments and may offer more options than your employer’s plan.

Option 3: Cash Out

You can cash out your 401(k), but this is generally not recommended. If you’re under 59½, you’ll pay a 10% early withdrawal penalty plus income taxes on the entire amount.

Option 4: Leave It with Your Old Employer

You can leave your 401(k) with your old employer if you have more than $5,000. But you won’t be able to make new contributions, and you might lose track of it over time.

Social Security and Medicare: Continuity Is Key

Good news: Social Security and Medicare taxes are continuous. Each employer withholds these taxes from your paycheck, and they all go toward the same Social Security and Medicare accounts. You don’t have to worry about losing credit for your contributions.

Social Security Wage Base

Remember, Social Security tax only applies to income up to the wage base ($184,500 in 2026). If you earned $100,000 at your old job and $100,000 at your new job, you’ll pay Social Security tax on the first $84,500 of your new job’s income ($184,500 - $100,000).

Unemployment Benefits: What You Need to Know

If you have a gap between jobs and collect unemployment benefits, those benefits are taxable at the federal level. Some states also tax unemployment benefits.

Tax Withholding on Unemployment

You can choose to have 10% withheld from your unemployment benefits for federal income tax. If you don’t, you’ll have to pay the taxes when you file your return.

Unemployment and Your Tax Return

You’ll receive a Form 1099-G showing the total amount of unemployment benefits you received. You must report this on your tax return.

Severance Pay: Is It Taxable?

Yes, severance pay is taxable. It’s considered supplemental wages, so your employer will withhold taxes using either the flat rate method (22%) or the aggregate method.

Severance Pay and Unemployment

Severance pay can affect your unemployment benefits. In some states, receiving severance pay can delay or reduce your unemployment benefits. Check with your state’s unemployment office for details.

Tax Treatment of Severance Pay

Severance pay is subject to:

• Federal income tax
• Social Security tax (up to the wage base)
• Medicare tax
• State income tax (if applicable)

Health Insurance: COBRA and Beyond

When you leave a job, you may be eligible for COBRA continuation coverage. COBRA allows you to keep your employer-sponsored health insurance for up to 18 months (or longer in certain circumstances).

COBRA Costs

COBRA premiums are generally more expensive than what you paid as an employee, because you’re paying both the employee and employer portions. You may also have to pay an administrative fee.

Alternatives to COBRA

If COBRA is too expensive, you might consider:

• A plan through the Health Insurance Marketplace (ACA)
• Spouse’s health insurance plan
• Short-term health insurance

Relocation Expenses: What’s Taxable?

If your new employer offers relocation assistance, the tax rules depend on the type of assistance:

Taxable Relocation Benefits

Most relocation benefits are taxable, including:

• Cash payments for moving expenses
• Payments for temporary housing
• Payments for house-hunting trips

Nontaxable Relocation Benefits

Some benefits may be nontaxable if they’re directly related to the move:

• Direct payment to a moving company
• Payment for storage of household goods

Stock Options and Restricted Stock Units (RSUs)

If you have stock options or RSUs from your old job, make sure you understand what happens when you leave:

Vested vs. Unvested Options

Vested options belong to you and can be exercised even after you leave. Unvested options are typically forfeited when you leave the company.

Taxes on Stock Options

When you exercise stock options or RSUs vest, you may owe taxes. The tax treatment depends on the type of options (incentive stock options vs. non-qualified stock options).

Tax Refunds When Changing Jobs

It’s common to get a tax refund when you change jobs, especially if you had multiple employers during the year. This is because each employer withholds taxes as if you’ll work there all year, resulting in overwithholding.

Example: Multiple Employers and Overwithholding

Sarah works at Job A from January to June, earning $40,000. She then starts at Job B in July, earning $60,000 for the rest of the year.

• Job A withholds taxes as if Sarah will earn $80,000 for the year
• Job B withholds taxes as if Sarah will earn $120,000 for the year
• Total withholding is higher than it would be if Sarah had one job all year
• Sarah gets a refund when she files her tax return

Common Mistakes to Avoid

Let’s talk about some common mistakes people make when changing jobs:

• Mistake: Forgetting to fill out a new W-4.
  Fact: Your new employer will use default withholding if you don’t fill out a W-4, which may not be correct for your situation.
• Mistake: Cashing out your 401(k) to pay bills.
  Fact: This results in taxes and penalties (if under 59½) and sets back your retirement savings.
• Mistake: Not adjusting withholding for multiple jobs.
  Fact: Each employer withholds as if you only have that job, which can lead to underwithholding.
• Mistake: Ignoring COBRA deadlines.
  Fact: You generally have 60 days to elect COBRA coverage after leaving your job.
• Mistake: Not saving your pay stubs and W-2s.
  Fact: You’ll need these documents when filing your tax return.

Checklist: Before You Leave Your Old Job

Here’s a checklist to help you stay organized:

1. Review your 401(k) and decide what to do with it
2. Check your stock options and RSUs
3. Review your health insurance options (COBRA vs. marketplace)
4. Save your final pay stub
5. Update your address with your employer (for W-2)
6. Check if you’re owed any unused vacation or sick pay

Checklist: When You Start Your New Job

Here’s what to do when you start your new job:

1. Fill out a new W-4 form
2. Enroll in health insurance
3. Set up your 401(k) contributions
4. Set up direct deposit
5. Review your first paycheck to ensure withholding is correct

How to Avoid a Large Tax Bill

To avoid a large tax bill when you file your return:

• Fill out your W-4 correctly
• Adjust your withholding if you have multiple jobs
• Make estimated tax payments if you have gaps between jobs
• Keep track of all your income (W-2s, 1099s, etc.)

Use our Tax Refund Calculator to estimate your refund or tax owed.