What are the estimated tax safe harbors?

You avoid federal underpayment penalties by paying, through withholding and timely estimates, the smaller of 90% of the current year's tax or 100% of last year's tax, which becomes 110% of last year's tax when prior-year AGI exceeded $150,000. High earners almost always plan around the 110% prior-year number because it is known and fixed.

When are quarterly estimated taxes due?

For 2026 income the federal due dates are April 15, June 15, and September 15 of 2026, and January 15 of 2027. The quarters are unequal, two months, two months, three months, four months, which surprises people who assume even spacing. States generally follow similar but not identical calendars.

My withholding stopped mid-year when I made partner. Does that help?

Yes, meaningfully. Tax withheld from your W-2 months is treated as paid evenly through the year, which retroactively covers early quarters. Many first-year partners can also front-load withholding from the final employee paychecks or a spouse's W-2 to patch an estimate gap, because withholding gets the even-spread treatment while estimates do not.

What happens if I miss an estimated payment?

The IRS charges an interest-based underpayment penalty per quarter, computed on Form 2210 at rates that have recently made underpaying genuinely expensive. It is not a cliff, and it is fixable: pay as soon as possible, use the annualized income method if income arrived unevenly, and increase later withholding where available.

Do partnerships withhold state taxes on my K-1?

Sometimes. Many states require partnerships to withhold on nonresident partners or offer composite returns where the firm pays state tax on your behalf. Those payments count toward your state liabilities but rarely cover a resident-state bill. Ask the practice administrator which states the firm handles and which are entirely yours.

Should I make estimated payments in a buy-in year with lower income?

Run both safe harbors before defaulting to 110% of your last employee year. A first partnership year reduced by buy-in interest or a partial-year allocation can make 90% of the current year the cheaper target. That takes a mid-year projection, which is exactly the appointment most new partners never book.

Physician Partnership Guide

Your First Year as a K-1 Partner

Nobody withholds anything for you anymore. This is the playbook that replaces the payroll department: safe harbors, quarterly deadlines, and the set-aside discipline.

A guide by Taxstra Tax & Accounting · CPA-led tax strategy for business owners

Your Guide

01What Changed and Why April Gets Ugly 02The Safe Harbor Decision 03The Transition-Year Playbook 04A Worked First Year 05Frequently Asked Questions

K-1 & Partnership Taxes>First-Year Partner Playbook

Written by Bryan Martin, CPA, Managing Partner and Founder of Taxstra. Last updated August 20, 2026.

Quick answer

In your first K-1 year, withholding stops and you pay tax through quarterly estimates: April 15, June 15, September 15, and January 15. High earners avoid penalties by paying 110% of the prior year's tax in even installments, skimming roughly 40% of each distribution into a tax account until a CPA refines the number.

The most expensive year of a physician's tax life is usually the first partnership year, and not because the tax rate changed. It is because the collection system changed and nobody told the new partner they were now running it.

As an employee, taxes left every paycheck before you saw the money. As a partner, the practice hands you gross distributions all year, then a K-1 in the spring. Between those two events, everything the payroll department used to do is your job. This playbook is that job, reduced to a few decisions and four deadlines.

What Changed and Why April Gets Ugly

Same income, no collection system.

Three collection mechanisms disappear at once: income tax withholding, the employee half of payroll tax coming out invisibly, and the employer half being someone else's expense. In their place: quarterly estimates covering income tax plus self-employment tax, on income you are taxed on as the practice earns it, not as you receive it.

The failure mode is always the same

The new partner keeps their employee spending habits, banks the fat distributions, and meets their real tax bill for the first time the following April: a year of tax, plus the first quarter of the new year due the same week, plus an underpayment penalty. Two years of tax obligations landing in one season. Every part of that is preventable with a set-aside account and four calendar entries.

The Safe Harbor Decision

Pay against last year's known number or this year's estimate.

Federal law does not require perfection, it requires a safe harbor: through withholding and timely estimates, pay the smaller of 90% of this year's tax or 100% of last year's, bumped to 110% of last year's when prior-year AGI exceeded $150,000, which describes virtually every physician making partner.

110% of last year

A fixed, known number from your final employee-year return. Divide by four, automate it, done. The default choice for a rising-income first partner year, because income above the estimate is penalty-protected.

90% of this year

Cheaper when this year will be lower: a partial-year allocation, heavy buy-in interest, or a group having a down year. Requires a real projection, updated mid-year, because guessing low buys the penalty back.

For 2026 income, payments are due April 15, June 15, and September 15, 2026, and January 15, 2027. Note the spacing: the second quarter is only two months long, the fourth is four.

Watch Out

The safe harbor covers penalties, not the bill

Paying 110% of your employee-year tax while earning partner income means a large balance due in April, penalty-free but still due. The set-aside account has two jobs: funding the quarterly estimates, and holding the difference between the safe harbor and the real tax so April is an administrative event, not a financial one.

The Transition-Year Playbook

The W-2 months are a tool. Use them.

Most physicians convert mid-year, which creates a quirk worth money: withholding is treated as paid evenly across the year no matter when it actually came out. Estimates are credited only when paid. So the withholding from your employee months quietly covers the early quarters, and if you see a gap coming, cranking up withholding on your last employee paychecks, or on a spouse's W-2 in December, patches earlier quarters retroactively in a way a late estimate cannot.

The state side needs its own list. Multi-state groups may file composite returns or withhold for nonresident partners in some states, while your resident state gets nothing unless you send it. Which states your K-1 touches is covered in the K-1 state filing guide; the first-year move is simply getting the list from the practice administrator and putting each state's estimate on the same calendar as the federal ones.

Taxstra CPA Tip

Open a separate high-yield savings account in week one and move a fixed percentage of every distribution into it before the money reaches checking. For most new physician partners the right opening number is around 40%, adjusted after a projection. The account earns interest until each deadline, and the discipline converts four scary deadlines into transfers.

A Worked First Year

A mid-year conversion, quarter by quarter.

Illustrative round numbers. Dr. Reyes earns $200,000 of W-2 wages through June with $45,000 withheld, makes partner July 1, and receives $250,000 of distributions in the second half. Her prior-year total tax was $90,000, so her 110% safe harbor is $99,000.

Her penalty-protection math

Safe harbor target (110% of $90,000)$99,000
Withholding, spread evenly by rule$45,000
Remaining to pay via estimates$54,000
September 15 and January 15 payments$27,000 each
Set-aside on distributions (40% of $250,000)$100,000 banked

The $100,000 set-aside funds the $54,000 of estimates with $46,000 still reserved, most of which meets the true-up in April, when her actual tax on the combined W-2 and K-1 year lands above the safe harbor. No penalty, no scramble, and her second year starts with a clean quarterly rhythm based on a full-year projection. The numbers are hypothetical; the sequence is the playbook.

Made Partner This Year and Nothing Is Set Up Yet?

The gap between "withholding stopped" and "estimates started" is where the penalties live. A Taxstra CPA can project your year and hand you the four payment amounts. The initial consultation is free.

Frequently Asked Questions

A workable starting point for a high-earning physician partner is 40% of each distribution into a separate tax account, refined once a CPA projects the actual year: federal bracket, self-employment tax, and your states. The precise number varies; the discipline of skimming every draw before spending it does not.

Walk Into April Already Square With the IRS

A one-hour projection in your first partner year beats any amount of cleanup in your second. Book a free initial consultation with a Taxstra CPA.

Next Steps

Filing it yourself is fine. Optimizing it is where the money is.

Getting the form right keeps you out of trouble. The strategies below are what actually lower the bill.

Want a CPA to run the numbers for you?

Free 30-minute call with a Taxstra CPA. No pressure, just the math for your situation.

Authoritative Sources

Citations reflect U.S. federal tax law as of the article's last reviewed date.

Related Physician Partnership Guides

Making Partner: W-2 vs K-1

The decision guide, if you have not signed yet.

Are Distributions Taxable?

Why your draw is not your taxable income.

Partner Health Insurance

The benefits shift that lands in the same year.

K-1 State Filing

Which states your K-1 makes you file in.