Safe Harbor (Estimated Tax)
Quick definition
A rule that protects you from an underpayment penalty if your estimated tax payments meet a set percentage of your prior-year or current-year tax.
The estimated tax safe harbor is the threshold of payments that protects you from an underpayment penalty, even if you still owe a balance when you file.
The common thresholds
Generally, you meet the safe harbor by paying at least 90% of the current-year tax or 100% of the prior-year tax through withholding and quarterly estimated payments. The prior-year figure rises to 110% for higher-income taxpayers.
Why it matters for drivers
Self-employed drivers owe self-employment tax plus income tax with no employer withholding. Hitting the safe harbor with quarterly payments is how you avoid a penalty on top of the bill. A larger mileage deduction lowers the tax those payments are measured against.
Related terms
Quarterly Estimated Tax
Four federal tax payments per year that self-employed workers make in lieu of W-2 paycheck withholding.
Self-Employment Tax
The 15.3% tax on net self-employment income that funds Social Security and Medicare.
Schedule C
The federal form self-employed workers use to report business income and expenses, including the mileage deduction.
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