Tag: January 15 estimated tax payment, fourth quarter estimated tax, safe harbor estimated tax, 110 percent safe harbor, estimated tax penalty, underpayment penalty, Form 2210, Form 1040-ES, annualized inc

Filing your 2025 return on extension locks in the prior year safe harbor for 2026 estimates. Steve Perry, EA explains how to recalculate the January 15, 2027 payment, why a large January payment does not erase earlier penalties, and how an equipment purchase can change which safe harbor target fits.