How should a travel therapist fill out a W-4 at a new agency?

Yes: each agency is a new employer, and federal rules require a signed withholding certificate on or before your first day with it, so the form you gave your last agency does not carry over. Fill it out for the year you expect, not just this contract, and rerun the IRS withholding estimator whenever you change agencies.

By ProTherapy Staffing, published November 8, 2026.

Why does every new agency ask for a W-4?

Because the rule attaches to each employer. The federal employment tax regulations say that “on or before the date on which an individual commences employment with an employer, the individual must furnish the employer with a signed withholding allowance certificate.” Form W-4 is that certificate.

The form states its purpose plainly: “Complete Form W-4 so that your employer can withhold the correct federal income tax from your pay.” A new agency has no copy of the form you gave the last one, and it does not see what you earned there. Whatever you put on the new form is all its payroll knows about your year.

What happens if you start without one?

The agency still has to withhold. The same regulation says that if an employee has no valid certificate in effect and “fails to furnish a valid withholding allowance certificate to the employer, the employee will be treated as single but having the withholding allowance provided in forms, instructions, publications, and other guidance prescribed by the Commissioner.”

In practice that means withholding at the single rate with none of your own adjustments. If you are married, claim dependents, or want extra withheld, nothing of that reaches your pay until you hand in a signed form. Do it during onboarding, with the rest of your new-hire paperwork, so the first check is figured on your own answers.

Do two agencies in one year count as two jobs?

Only if they overlap. The form’s multiple jobs step says to complete it if you “hold more than one job at a time, or” are married filing jointly with a working spouse. Back-to-back contracts with different agencies are one job after another; a contract plus a weekend per diem job, or two agencies at once, are jobs at the same time.

The IRS explains why it matters: “Tax rates increase as income rises, and only one standard deduction can be claimed on each tax return, regardless of the number of jobs.” Each payroll withholds as if its job were your only one, so two at once usually under-withhold together. When you have overlapping jobs, the FAQ says you enter the extra amount “on the Form W-4 for only one of the jobs.”

If you want to see how an offer splits taxable pay and stipends before you fill in the form, ask a ProTherapy recruiter: Find my next contract.

Why can a travel contract leave you owing at tax time?

Withholding follows the wages payroll sees, and on a typical travel contract the taxable wage is only part of the weekly pay. Estimated payments explains why that can leave the year’s withholding short, especially with state taxes or other income on top. A year split across several agencies, each starting your withholding fresh, can add to the gap.

The IRS FAQ says that if you do not adjust for multiple jobs or for other income, “you will very likely owe additional tax when filing your tax return, and you may owe penalties.” It also gives the choice: “For income from sources other than jobs, you can pay estimated tax instead of having extra withholding.” Extra withholding on the W-4 comes out of every check without a separate payment to remember; quarterly payments keep more in each check and take discipline.

When should you run the IRS withholding estimator?

At each agency change, and at the start of the year. The IRS Tax Withholding Estimator page says to “check your withholding every January to make sure it’s correct for the year,” and to check again after a major life change, including a “new job or other paid work.”

Bring your most recent pay stubs from every agency you worked for this year; the estimator asks for them. At the end it can produce a completed Form W-4 for you to give the new agency. The page also warns that “if you change your withholding during the year, you may need to update it again in late December to withhold the right amount next year.”

What should you check after the first paycheck?

Find the federal income tax line on the first stub and compare it with what the estimator expected. If it is far off, ask payroll which filing status and extra amount they have on file; a form that was never processed looks the same as one filled in wrong. The form’s own header adds that “your withholding is subject to review by the IRS.”

The W-4 covers federal income tax only. Ask the new agency’s payroll what it needs for the state you will work in, and keep each agency’s stubs together for year-end. If your year mixes several states, a preparer who works with travelers can set your withholding with you before the gap grows.

Frequently asked questions

Do I need a new W-4 for every travel agency?

Yes. Federal rules require a signed withholding certificate on or before the day you start with each employer, and an agency has no copy of the form you gave another one.

What happens if I don't turn in a W-4?

The agency still withholds, treating you as single with the standard withholding the IRS sets, so none of your own adjustments, such as a married filing status or extra withholding, apply until you hand in a signed form.

Do back-to-back contracts count as multiple jobs on a W-4?

No. The multiple jobs step is for holding more than one job at a time. Contracts with different agencies one after another are not at the same time; a contract plus a second job, or two agencies at once, are.

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