One of the most frustrating surprises at tax time?

Owing the IRS more than expected—plus a penalty.

Underpayment penalties are more common than most people think, especially for business owners, freelancers, and anyone with income not fully taxed throughout the year.

An underpayment penalty happens when you don’t pay enough in taxes during the year—either through withholding or estimated payments.

The IRS expects you to pay as you go, not just settle up in April.

We see this most often with:

• Self-employed individuals
• S corporation owners
• Rental property owners
• Anyone with multiple income sources

If taxes aren’t being withheld automatically, it’s easy to fall behind without realizing it.

Common causes include:

• Not making quarterly estimated payments
• Underestimating income
• Relying on last year’s numbers when income has increased
• Not adjusting withholding after major life or business changes

Even if you pay your full tax bill at filing, you can still face a penalty if payments weren’t made throughout the year.

The IRS provides a few “safe harbor” guidelines to help you avoid penalties:

• Pay at least 90% of your current year’s tax, or
• Pay 100% of last year’s tax (110% for higher incomes)

Staying within these thresholds can help you avoid penalties—even if you still owe at filing.

Underpayment penalties aren’t just about what you owe—they’re about when you pay it.

Proper tax planning allows you to:

• Stay compliant
• Avoid penalties and interest
• Manage cash flow more effectively

Underpayment penalties are avoidable—but only if you’re paying attention to your numbers year-round.

At Profit Wise Accounting & Tax, we help you stay ahead of your tax obligations so there are no surprises—just a clear plan and confidence moving forward.