For small business owners, freelancers, and entrepreneurs, quarterly estimated taxes are one of the least exciting but most important parts of financial management. Unlike employees who have taxes withheld automatically from their paychecks, business owners must calculate and pay taxes directly to the IRS on a quarterly basis. Missing these deadlines or paying less than what you owe can lead to costly penalties and interest charges. According to the IRS, millions of taxpayers are assessed underpayment penalties each year. In 2023, the IRS collected more than $1.5 billion in penalties related to estimated tax underpayments. For a small business owner, these…