Tax foundations

Start here to understand the pieces of a federal tax estimate. A tax bracket applies to a slice of taxable income; it does not apply to every dollar you earn. The guides distinguish gross receipts, adjusted income, taxable income and payments already made. They also explain why an LLC label, a refund amount or a withholding percentage cannot tell you your total liability. Use the foundations guide as a map, then choose the page that matches your question. These pages focus on individual federal income tax and ordinary sole-proprietor situations in the United States. They do not replace state guidance or determine eligibility for a credit. For any decision, use the tax year that matches the income being reported and verify exceptions with the linked IRS instructions.