Why you probably need them, how to calculate them, and when to pay.
Here's the issue: a large portion of your compensation (stipends) is non-taxable. That means your W-2 wages are lower, so the taxes withheld from your paycheck are based on a smaller number. But your actual tax liability may be higher — especially when you add state taxes from multiple states.
If your withholdings don't cover your full tax bill, you'll owe the balance at tax time. If the shortfall is more than $1,000, the IRS charges underpayment penalties. Quarterly estimated payments prevent this.
You likely need them if: Your stipends represent a large portion of your total compensation (common for most travelers). You work in states with income tax but your withholdings only cover federal. You have additional income beyond your travel therapy wages. Your CPA tells you your projected liability exceeds withholdings by more than $1,000.
You may NOT need them if: Your tax home is in a no-income-tax state AND you only work in no-tax states. Your taxable hourly rate is high enough that withholdings cover everything. You had zero tax liability last year (safe harbor rule).
Q1: April 15 (for income earned Jan-Mar)
Q2: June 15 (for income earned Apr-May)
Q3: September 15 (for income earned Jun-Aug)
Q4: January 15 of following year (for income earned Sep-Dec)
Miss a deadline and interest starts accruing on that quarter's underpayment immediately.
The simplest approach is the safe harbor method: pay at least 100% of last year's total tax liability in estimated payments this year (110% if your AGI was above $150,000). This protects you from penalties regardless of what you actually owe.
For a more precise approach, estimate your current-year tax liability using your projected income, stipend amounts, and expected deductions. Subtract your expected withholdings. The difference is what you owe in estimated payments, divided into four quarters.
Federal: IRS Direct Pay (irs.gov/payments) is free and instant. You can also use EFTPS (Electronic Federal Tax Payment System) if you prefer to schedule payments in advance. Use Form 1040-ES vouchers if paying by mail.
State: Each state has its own payment portal. Pay estimated taxes to your tax home state and to each state where you earned income. Your CPA can tell you which states need estimated payments based on your assignment history.
Forgetting state estimated payments. You may owe quarterly payments to 2-3 states, not just federal. Missing state payments results in state-level penalties.
Using last year's permanent-job taxes as your baseline. Your tax situation is completely different as a traveler. Recalculate for your travel therapy income structure.
Stopping estimated payments when you take time off. If you earned income earlier in the quarter, you may still owe for that period.
For the full tax picture, start with our main tax guide and state tax overview.
Connect with experienced travel therapy tax professionals.