Tax Planning
Quarterly Estimated Taxes for 1099 Physicians: A Working Guide
By the Attend Wealth team · Updated August 2026 · 8 min read
Physicians with 1099 income are usually not underpaying out of carelessness. They are underpaying because nobody told them the safe harbor threshold changes above a certain income.
Quick answer
You avoid an underpayment penalty by meeting either safe harbor: paying at least 90% of the current year's tax, or paying 100% of the prior year's total tax. If your prior-year adjusted gross income exceeded $150,000, that second test rises to 110%, which captures most attending physicians. Married filing separately hits the threshold at $75,000. Whichever test produces the smaller payment is the one you need to meet.
The two safe harbors
Safe harbor rules give you a target that ends the question. Hit it and no underpayment penalty applies, even if you owe a large balance at filing. You need to satisfy only one of the two tests, and you get to use whichever produces the smaller required payment.
The first test is paying at least 90% of the tax you will actually owe for the current year. The second is paying 100% of the total tax shown on your prior year's return. The second is usually easier to compute because it uses a number you already have.
The 110% rule that catches attending physicians
If your adjusted gross income for the prior year exceeded $150,000, the prior-year safe harbor is not 100%. It rises to 110%. For married taxpayers filing separately, the threshold is $75,000 of prior-year AGI.
Most attending physicians clear $150,000, which means the rule that applies to them is not the one described in most general-audience tax articles. A physician who dutifully pays 100% of last year's tax and believes they are protected is short by ten percent of a large number.
The residency-to-attending trap
The prior-year safe harbor is unusually generous in the year your income jumps. A physician who earned $65,000 as a PGY-4 and $340,000 in their first attending year can pay based on the prior year's much smaller tax bill and still be penalty-protected.
The catch is that this only defers the problem. The actual tax on $340,000 comes due at filing, and it is large. Physicians who use the prior-year safe harbor in the transition year should be setting the difference aside deliberately, not spending it, because April will ask for it in one payment.
Mechanics and timing
Form 1040-ES contains the worksheet for computing what you owe, and each quarterly installment is generally 25% of the annual total. The due dates do not fall evenly across the calendar, which surprises people every year.
One useful wrinkle for physicians with both W-2 and 1099 income: withholding from a W-2 job is treated as paid evenly across the year regardless of when it was actually withheld. So increasing W-2 withholding late in the year can cure an earlier shortfall in a way that a late estimated payment cannot.
- Compute the prior-year safe harbor first; it is usually the simpler target
- Apply 110%, not 100%, if prior-year AGI exceeded $150,000
- Use Form 1040-ES to compute installments
- Consider increasing W-2 withholding to cure a shortfall, since it is treated as paid evenly
- Set aside the gap in a transition year rather than spending it
State estimated taxes are a separate obligation
State rules differ and are not covered by meeting the federal safe harbor. Locums physicians working across state lines can owe estimated payments in multiple states, each with its own thresholds and due dates.
This is the single most common source of surprise penalties for locums physicians, and it is worth resolving with a CPA who has handled multi-state physician returns rather than assuming the federal calculation carries over.
Related physician planning questions
What is the 110% safe harbor rule?
If your prior-year adjusted gross income exceeded $150,000, you must pay 110% of the prior year's total tax to use the prior-year safe harbor, rather than 100%. For married filing separately the threshold is $75,000 of prior-year AGI.
How do 1099 physicians avoid an underpayment penalty?
Meet either safe harbor: pay at least 90% of the current year's tax, or pay 100% of the prior year's total tax, rising to 110% if prior-year AGI exceeded $150,000. You only need to satisfy one, and you may use whichever produces the smaller payment.
Can I fix an underpayment late in the year?
Often yes, if you have W-2 income. Withholding from wages is treated as paid evenly throughout the year regardless of when it was actually withheld, so increasing W-2 withholding late in the year can cure an earlier shortfall in a way a late estimated payment generally cannot.
Do state estimated taxes follow the federal safe harbor?
No. State rules are separate and vary. Locums physicians working across state lines may owe estimated payments in multiple states, each with its own thresholds and deadlines.
What happens in the year I go from resident to attending?
The prior-year safe harbor is based on your much lower training income, so your required payments are small and you remain penalty-protected. But the actual tax on attending income still comes due at filing, so set the difference aside rather than spending it.
Related insights
- Estimated Taxes for Locums Physicians
- Quarterly Taxes for 1099 Doctors
- W-2 vs. 1099 Physician Taxes
- Browse the full archive
Sources
- Internal Revenue Service — Form 1040-ES, Estimated Tax for Individuals (accessed August 2026)
- Brighton Jones — Safe Harbor Tax Rules and Estimated Tax Payments (accessed August 2026)
- TurboTax — Estimated Taxes: How to Determine What to Pay and When (accessed August 2026)
Figures current as of August 7, 2026. Contribution limits, tax thresholds, and federal loan program rules change; verify against the primary source before acting.
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