Most small business owners are scrambling to figure out Q1 estimated taxes at the last minute. Smart entrepreneurs are using safe harbor rules to legally minimize their quarterly payments by up to 40% while staying completely compliant. Here's what your accountant probably hasn't told you: The IRS collected $4.2 billion in estimated tax penalties last year , most of it from business owners who either overpaid unnecessarily or underpaid due to confusion about the rules. Quic