For your 2025 return you file in 2026. You need to make quarterly estimated payments based on when you get the income. Or you can increase any withholding during the year to cover the extra income.
You will pay Self Employment tax (Scheduled SE) on a Net Profit of $400 or more on Schedule C in addition to regular income tax on it. You pay 15.3% SE tax on 92.35% of your Net Profit (If it is greater than $400). The 15.3% self employed SE Tax is to pay both the employer part and employee part of Social Security and Medicare. So you get social security credit for it when you retire.
Turbo Tax guide to Estimated taxes
A Guide to Paying Quarterly Taxes - TurboTax Tax Tips & Videos
You must make quarterly estimated tax payments for the current tax year if both of the following apply:
- 1. You expect to owe at least $1,000 in tax for the current tax year, after subtracting your withholding and credits.
- 2. You expect your withholding and credits to be less than the smaller of:
90% of the tax to be shown on your current year’s tax return, or
100% of the tax shown on your prior year’s tax return. (Your prior year tax return must cover all 12 months).
To prepare estimates for next year you start with your current return, (if you can't get back into your return try this, On the Tax Timeline page you have to select Add A State to get back into your return). But be careful not to change anything on your real return.
Go to Federal Taxes or Personal (Home&Business version)
Other Tax Situations
Other Tax Forms
Form W-4 and Estimated Taxes - Click the Start or Update button
Say No to W4. When you get to the W4 and Estimated Taxes section, say you want to adjust your income to go though all the screens.
The 1040ES quarterly estimates are due April 15, 2025, June 16, Sept 15 and Jan 15, 2026. Your state will also have their own estimate forms.
Or here are the blank Estimates and instructions (the actual 1040ES forms are at the very bottom so scroll way down)
http://www.irs.gov/pub/irs-pdf/f1040es.pdf
