A recent GOBankingRates report highlights five common tax mistakes that can cost American taxpayers thousands of dollars annually, with the April 15 deadline approaching. These errors range from failing to claim available deductions and track deductible expenses like charitable contributions or medical costs, to misreporting investment income and stock compensation due to incorrect tax basis calculations. Additionally, individuals, particularly small business owners and the self-employed, may face penalties for missing estimated tax payments, while failing to update withholding after life events like marriage or having a child can lead to overpayment. Poor recordkeeping and simple filing errors, such as mathematical mistakes or typos, can also result in delayed refunds or IRS audits, underscoring the importance of proactive tax management beyond the annual filing season.