The 40 tax threshold is not a commonly used term in tax law. However, the income tax threshold is the income level at which a person begins paying income taxes. The tax threshold varies by country and is often adjusted annually. For example, in the United States, there are seven federal income tax brackets for the 2023 tax year, ranging from 10% to 37% . The income thresholds for each bracket depend on the taxpayers filing status, such as single, married filing jointly, married filing separately, or head of household. Taxpayers are taxed at a marginal rate, meaning that each rate applies only to a specific slice of income, rather than to their total income. Therefore, the amount of tax owed depends on the taxpayers taxable income, which is their gross income minus any deductions or exemptions they are eligible for.