Ways to Pay Tax on Your Locums Income
When you work locums, you're self-employed, and nobody is withholding taxes for you. So how and when do you actually make those tax payments? Here's what you need to know.
There are three ways to pay tax on your locums income: make estimated tax payments, withhold more at a W-2 job, or just owe on April 15th. Estimated tax payments are the most common approach.
Make Estimated Tax Payments
If you bring in a decent amount of locums income, you'll most likely need to make quarterly estimated tax payments. Here's when and how.
Due Dates
The due dates for estimated tax payments are:
Q1 (Jan-Mar): April 15
Q2 (Apr-May): June 15
Q3 (Jun-Aug): September 15
Q4 (Sep-Dec): January 15
How to Pay
There are two ways to pay estimated taxes: by mail or online. Mail is still more common, but paying online is faster and more secure.
To pay by mail, send a check along with a payment voucher (Form 1040-ES). Your tax preparer or DIY tax software will generate this form for you.
We're big fans of paying online. As of this writing, the URL is https://www.irs.gov/payments. You can pay from your bank account, or with a debit or credit card. Perhaps the best feature: you can schedule payments for a future date. If you know how much you want to pay for several upcoming quarters, you can schedule it all at once and be done.
Two tips for paying online:
If you file jointly, use the Social Security number of the spouse listed first on your tax return. This ensures the IRS credits the payment correctly.
You can modify or cancel a scheduled payment up to two business days before the payment date. Ideally you won't need to make changes — but if you do, don't wait until the last minute.
Withhold More at a W-2 Job
Another way to cover your locums tax is to increase withholding at a W-2 job — yours or your spouse's. Here's when this works and how to do it.
Benefits of Withholding More
This approach is underrated. Two key benefits:
You skip estimated tax payments entirely, saving you time.
All your locums income is yours to keep, since the tax is already covered.
When It Works Best
Withholding more at a W-2 job works best when you're doing a modest amount of locums on the side. Since the added tax burden isn't huge, you'll still take home a decent paycheck even after increasing withholding.
This matters most if you're asking your spouse to withhold more at their job. Many spouses aren't thrilled to see their take-home pay drop, even knowing it's going toward the same household tax bill.
How to Withhold More
You do this by making new withholding elections — talk to HR at your W-2 job if you need help.
HR may ask you to complete a new Form W-4 to update your elections. Fair warning: this form is complex enough that filling it out often leaves you with little confidence the right amount will actually be withheld.
Pro tip: Look at your current withholding and add a flat dollar amount instead. This is the most reliable way to get the result you want on the first try. Say your current withholding is $1,000 per paycheck and you want to get to $1,500 — just tell HR to withhold an extra $500 per check. If you do fill out Form W-4, line 4(c) lets you write in that extra amount directly.
Owe on April 15th
Whatever you didn't cover through estimated payments or W-2 withholding, you'll owe when you file. That's fine, as long as you know what to expect.
You're technically supposed to pay tax on locums income throughout the year, not all at once. If you underpaid, you may see a penalty on your return. It's a manageable cost, but worth avoiding if you can.
Want to go deeper? Check out our complete guide to locum tenens taxes.
Ready to put this into practice? If you're an ER physician or high-income professional looking for straightforward, evidence-based financial guidance, we'd love to connect. Schedule a free intro call with Yahara Wealth Management — no pressure, no sales pitch, just a conversation.
This article is for general educational purposes only and does not constitute personalized tax, legal, or investment advice. Everyone's tax situation is different — consult a qualified tax professional before making decisions about estimated payments or withholding.