What are the most common write-off myths that get people in trouble?

A few myths recur. First, "I can write off my whole car" — only business-use miles or the business percentage of costs count, never commuting or personal trips. Second, "buying equipment in December saves more than it costs" — a deduction returns only your marginal tax rate, so spending $1,000 to save maybe $300 is a loss unless you needed the item. Third, "any meal with shop talk is deductible" — it must have a genuine business purpose and is only 50%. Fourth, "clothing for work counts" — only uniforms or gear unsuitable for everyday wear. Fifth, "my dog/gym/vacation is a business expense" — almost never. Sixth, treating distributions as a way to skip a reasonable S-corp salary. Deductions reduce taxable income, not your tax bill dollar-for-dollar, so never spend money purely to "save on taxes." Keep records that prove business purpose.