With ten days left before the October 15 extended deadline, here's a practical checklist to work through — filing status, balance due, retirement contributions, and the FBAR deadline that closes the same day.

A valid extension protects against the failure-to-file penalty. It does nothing for the Section 6654 estimated tax underpayment addition, which is measured against the original quarterly due dates — not the extended filing date.

The third estimated tax installment was due September 15. If you missed it, here's how the penalty is actually calculated, what still reduces it, and what doesn't.

The individual estimated-tax penalty is based on required installments during the year, not merely the balance due with the return. Current-year tax, prior-year tax, adjusted gross income, withholding timing, annualized income, exceptions, and waivers all matter.

If you’re self-employed or own a business that doesn’t withhold taxes from your income, the IRS expects you to pay taxes throughout the year — not just at filing time. These are quarterly estimated tax payments, and getting them wrong is one of the fastest ways to end up with a penalty you didn’t see coming. Here’s how estimated taxes actually work, when they’re due, how to calculate them, and how to avoid the most common mistakes. Who Needs to Pay Estimated Taxes If you expe