Physician Advisor Match

Physician Quarterly Estimated Tax Calculator

If you have 1099 income from locum tenens, moonlighting, or a private practice, the IRS expects you to prepay taxes in four installments throughout the year. Miss them and you'll owe an underpayment penalty at tax time — even if you pay your full bill in April. This calculator estimates your 2026 quarterly payment amounts and shows whether you're on track for the safe harbor.

W-2 income (hospital / employer)

Leave at zero if you're purely 1099/locum.

2026 employee deferral limit: $24,500 (<50) / $32,500 (≥50); ages 60–63: $35,750
Find on your most recent pay stub (YTD federal income tax withheld). Enter 0 to estimate from withholding tables.

1099 / self-employment income

Enter net income after deductible business expenses (malpractice, CME, home office, equipment, etc.).

Gross 1099 receipts minus Schedule C deductions. See physician tax deductions guide.
Reduces income tax but NOT self-employment tax. 2026 limit: $24,500 (<50). See solo 401(k) guide.

Safe harbor inputs

Line 24 on your 2025 Form 1040. Used to compute your safe harbor amount (110% of prior year for most physicians).
Total quarterly payments already submitted to the IRS in 2026 (not W-2 withholding — that's above).

Your 2026 estimated tax summary

Tax liability estimate

W-2 gross wages
W-2 pre-tax deductions
Net 1099 / SE income
SE tax deduction (50% of SE tax, above-the-line)
Solo 401(k) employee deferral
Standard deduction
Federal taxable income
Federal income tax (brackets)
Self-employment tax (Social Security + Medicare)
Total estimated federal tax

What you still owe

W-2 federal withholding
Estimated payments made so far in 2026
Net balance requiring estimated payments

Safe harbor & quarterly schedule

Quarter Income period Due date Recommended payment
About these estimates

This calculator estimates federal income and self-employment taxes using 2026 brackets and limits. It does not include state income tax, NIIT on investment income, AMT (alternative minimum tax), QBI deduction for practice owners, or Roth IRA contribution limits. Use these figures for planning; work with a tax professional for your return.

Why physicians get hit with underpayment penalties

W-2 employees have taxes withheld from every paycheck automatically. When you add 1099 income — from locum tenens work, moonlighting, expert witness fees, or speaking honoraria — that income arrives gross, with nothing withheld. If you don't make quarterly estimated payments, the IRS treats it as if you deliberately delayed, and charges an underpayment penalty (currently around 8% annualized) on the shortfall.

The penalty applies even if you write a check for the full amount on April 15. The IRS wants a portion of each quarter's liability paid within that quarter.

The safe harbor rule — the easiest way to avoid penalties

The IRS offers a safe harbor: if your total payments (withholding + quarterly estimated payments) equal at least the safe harbor amount, you avoid underpayment penalties regardless of your actual tax bill.

2026 safe harbor thresholds:
  • If your 2025 AGI was ≤ $150,000: pay 100% of your 2025 total federal tax (Form 1040, line 24) across four equal quarterly installments.
  • If your 2025 AGI was > $150,000 (most physicians): pay 110% of your 2025 total federal tax — again in four equal installments.
  • Alternatively: pay 90% of your 2026 actual tax liability across the four quarters. This approach requires a good estimate of your current-year income.

Most physicians use the 110%-of-prior-year method because it's predictable. You don't have to re-estimate your income each quarter — just divide last year's tax bill by 4, multiply by 1.1, and pay that amount each quarter.

Self-employment tax: the component most physicians underestimate

When you earn 1099 income, you pay both the employee and employer share of FICA — a combined 15.3% on the first $184,5001 of net self-employment earnings (Social Security 12.4% + Medicare 2.9%), then 2.9% on earnings above that. For a physician netting $100,000 from locum work, that's roughly $14,130 in SE tax on top of regular income tax.

There is one partial offset: you deduct 50% of SE tax as an above-the-line deduction before computing income tax. The calculator includes this automatically. See the locum tenens financial guide for the full tax picture on 1099 physician income.

Common physician scenarios

Hospital attending + moonlighting

W-2 income may have adequate withholding for the employed portion. The moonlighting 1099 income — $30,000–$80,000 for a typical ER or hospitalist shift-based arrangement — requires separate quarterly payments. SE tax alone on $60,000 net moonlighting income: ~$8,478.

Full-time locum tenens

All income arrives 1099 with zero withholding. Estimate: a locum hospitalist earning $250,000/year (net after expenses) owes roughly $35,000–$55,000 in SE tax plus federal income tax depending on filing status. First-year locums routinely get surprised by this in April.

New attending transitioning from residency

Prior year AGI was $60,000 in residency. Your safe harbor this year is 100% of that small residency tax bill — very manageable. But your actual 2026 tax liability as an attending will be 4–8× higher. Plan for the April catch-up payment.

Private practice owner

Practice revenue minus deductible expenses = SE income. SE tax applies to your share of net earnings (up to SS wage base). An S-corp election lets you split income into W-2 salary (FICA only) and distributions (no SE tax), reducing the SE tax bill substantially above ~$80,000 net.

How to actually make the payments

Use IRS Direct Pay (irs.gov/payments) or the IRS2Go app. Select "Estimated Tax" as the reason and "1040-ES" as the tax form. You can also mail Form 1040-ES with a check. Set a recurring calendar reminder for each due date — there's no automatic notice from the IRS when a quarter is coming.

2026 quarterly deadlines:

Strategies to reduce quarterly payments

The most effective lever for physicians with 1099 income: maximize deductible retirement contributions. A solo 401(k) lets you defer up to $72,000/year (2026, employee + employer contributions2), directly reducing income subject to income tax. The S-corp election can cut SE tax by 20–30% on the income above a reasonable W-2 salary — see the S-corp savings calculator.

For broader tax strategy including QBI, practice structures, and cash balance plans, see the physician tax strategy guide and physician tax deductions guide.

  1. IRS — Self-Employment Tax (SE Tax); SS wage base $184,500 for 2026 per IRS IR-2025-244.
  2. IRS — One-Participant 401(k) Plans; 2026 §415 limit $72,000 per IRS Notice 2025-67.
  3. IRS — Form 1040-ES, Estimated Tax for Individuals; safe harbor rules §6654.
  4. IRS Rev. Proc. 2025-67 — 2026 inflation adjustments including income tax brackets, standard deductions, and contribution limits.

Tax values verified against 2026 IRS guidance as of June 2026.

Get your estimated tax strategy reviewed by a physician-specialist

Quarterly estimated taxes are one piece. A physician-specialist advisor can layer in the right retirement account structure, S-corp election timing, and deduction sequencing to legitimately reduce the amount you owe — not just help you pay the right amount on time. Fee-only, no product sales.